483 FXUS63 KGRR 180800 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 400 AM EDT Mon May 18 2026 .KEY MESSAGES... - Slight Risk for Severe Storms Today - Slight Risk for Severe Storms on Tuesday - Drier and cooler mid to late week && .DISCUSSION... Issued at 400 AM EDT Mon May 18 2026 - Slight Risk for Severe Storms Today The storm prediction center has placed Southwest Lower Michigan in a slight risk for severe weather today. Clouds and showers will try to press in from the west this morning which will decrease somewhat how much we can destabilize. 500mb flow will be weakening as we move through the day as well which is another negative factor with regard to severe weather chances. What we are watching though is the chance that the current activity redevelops or regenerates over our area after about noon (this is seen in the HREF). We feel that between roughly 100pm and 700pm there is chance for severe weather, especially south and east of a line from Whitehall to Clare (so the bulk of the area). An item of note in the HREF is the 850mb low level jet ramps up during the afternoon to 40-45 knots. The LLJ increase is seen most for areas near and southeast of GRR including AZO, LAN and JXN. These areas stand the best chance at some damaging winds this afternoon and evening. The Nadocast machine learning website also sees wind as our biggest threat today over our southeast half of the forecast area. There is a chance for some scattered storms tonight, but nothing that looks widespread. - Slight Risk for Severe Storms on Tuesday Another slight risk for severe storms is in place for Tuesday over the southeast CWA. The setup is similar in that decaying showers and storms will move in during the morning with a threat of redevelopment over our area in the afternoon. Tomorrow's threat though looks more confined to the southeast CWA, essentially a smaller threat area including AZO, LAN and JXN. Today we have some threat outside of those areas, but tomorrow (Tuesday) the best chances may very much be confined to those areas. Deep layer shear on Monday is 25-35 knots and Tuesday that increases to 30-40 knots. So some storm organization is possible especially with Tuesday's threat. Again though, the morning clouds and showers may dampen our threat a bit. - Drier and cooler mid to late week The cold front will sweep through the forecast area Tuesday evening. Much drier air will invade from the north with PWAT values plummeting from 1.7 inches Tuesday morning which is off the chart for this time of year to less than 0.5 inches on Wednesday. It will be noticeably cooler with highs in the 60s Wednesday and Thursday. Wednesday night we are likely looking at frost across Central Lower Michigan. Another systems looks to bring some rain out towards Friday, but the models have had difficulty coming to a consensus. The trend though looks to be towards rain on Friday. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 214 AM EDT Mon May 18 2026 There are two main aviation concerns today, the first being the chance of thunderstorms and the second being gusty south winds. As for the chance of thunderstorms, a line of weakening showers/storms is located off to the west over Wisconsin and Iowa at 06z. These showers/storms will continue to slowly move our direction and will begin to move into the area after 13z. We expect a weakening line of activity that should mainly be showers at that point. An uptick in activity or a redevelopment will occur between 16z and 18z as the activity move through Southwest Lower Michigan. A period of more substantial showers and some strong storms will be possible between 18z and 23z. After 23z, the activity should wind down and/or move off to the east. Conditions will largely be VFR outside of the short periods that the activity affects any one TAF site. As for the wind, shortly after daybreak or around 13z we expect winds to ramp up out of the SSW from 190-210. Speeds through the bulk of the day will be between 15-30 knots. && .MARINE... Issued at 400 AM EDT Mon May 18 2026 We have extended the Small Craft Advisory both in time and areal extent. The SCA now runs through Tuesday for all zone. The southern two zones, south of Holland, begin tonight. Strong southerly winds will continue both today and Tuesday as we remain east of the cold front the bulk of that time. South winds of 15 to 25 knots look common with waves of 3 to 6 feet. The SCA may need to be extended into Tuesday night for a period of stronger northwest winds behind the cold frontal passage. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory from 2 AM to 8 PM EDT Tuesday for LMZ844- 845. Small Craft Advisory until 8 PM EDT Tuesday for LMZ846>849. && $$ DISCUSSION...Duke AVIATION...Duke MARINE...Duke  958 FXUS62 KMFL 180807 AFDMFL Area Forecast Discussion National Weather Service Miami FL 407 AM EDT Mon May 18 2026 .KEY MESSAGES... Updated at 405 AM EDT Mon May 18 2026 - High risk of rip currents along the east coast of South Florida will continue through at least Tuesday evening as breezy easterly winds prevail. - Scattered showers and thunderstorms will develop mainly across SW Florida again today. Low-end chance for an isolated severe thunderstorm. Rain chances will remain elevated over the next several days. && .SHORT TERM... (Today through Tuesday) Issued at 119 AM EDT Mon May 18 2026 South Florida is going to be sandwiched between an upper level low centered near the Bahamas and a ridge of high pressure over the deep south and Gulf. The low over the Bahamas will usher in some positive vorticity pulses from the northeast and increase instability across the area. The easterly flow has a chance to become more dominant than yesterday, meaning that the Gulf breeze may not be able to move inland at all. However, much of the guidance does have it forming and getting stuck just barely on land. If this boundary does move more inland it will get pinned no further than along the metro areas of Collier county and Naples. SBCAPE is forecast to be 2000-3000 J/kg with steep low level lapse rates of 8-9 C/km and 500mb temps near -10 deg C. The dry air column has mostly been eroded, although some level of dry air still remains in the mid-levels along with an inverted-V profile on model soundings. This suggests that a couple of storms could become marginally severe again via wind gusts. Additionally, with these steep low level lapse rates and increased CAPE, updraft health has a good chance to be sustained even with the inhibition of the upper level ridge. Given the upper level ridge presence, the risk for strong to severe storms is highly conditional again today, but with the parameters explained above, support is there for an isolated severe thunderstorm or two occurring along the Gulf breeze where the strongest lift and near-surface convergence occurs. Both severe winds and quarter-size hail will be possible today. On Tuesday, the weather pattern remains largely the same although its more uncertain to determine severe potential. The easterly flow will remain in place and result in another day with a Gulf breeze that gets trapped from advancement, but 500mb temps will rise a couple of degrees to -8 deg C and some extra dry will filter in the mid-levels, which will lower instability. Nevertheless, typical wet season scattered showers and storms are still expected on Tuesday with most of the activity occurring in Southwest Florida with the ongoing easterly flow regime. High temperatures for today and Tuesday will again range from the mid to upper 80s in Southeast Florida to the low to mid 90s for Southwest Florida. && .LONG TERM... (Tuesday night through Sunday) Issued at 1257 AM EDT Mon May 18 2026 Longwave ridging will be the dominant pattern aloft for the eastern CONUS during the middle portion of the week. Florida will find itself in between an H5 centroid to its west over the southern Gulf and an H5 centroid to its east near Bermuda. Within the overall ridging pattern, ensemble guidance is in pretty good agreement of showing a cut off low meandering around the northern Caribbean just east of the Bahamas. This area of low pressure will provide increased forcing for storms over the Atlantic waters as several lobes of vorticity advect westward near the vicinity of the Florida coastline. Florida will remain under rich moisture through the period, but some deeper pockets look to raise PWATs to near 1.8 inches, which is within the 75th percentile for this time of year. At the surface, winds will remain mostly easterly, but wind speeds will be slightly weaker than in the beginning of the week as pressure gradients relax across the eastern seaboard. As a result of this predominant easterly flow, the Gulf breeze won't be able to advance as far east. This will result in most afternoon thunderstorm activity favoring interior and portions of southwest Florida each day. Overall, PoPs will generally be in the 30% to 40% range across the peninsula each day, with higher 55% to 65% PoPs along the sea breeze convergence zones. Main threats will be frequent lightning, locally heavy downpours, and gusty winds. Despite the cutoff low nearby, 500 mb heights will actually be between 586 to 589 dm across South Florida, which is near to slightly above average for this time of year. This will in turn lead to slightly above normal temperatures area wide, with high temperatures in the upper 80s and low 90s. With moisture staying steady throughout the week, heat indices will remain in the upper 90s and lower 100s through the period as well. Zooming into the forecast a little bit, diurnal heating will drive most of these high temperatures each afternoon. But, with increased chances of showers moving onshore from the Gulfstream during the morning (particularly for the middle part of the week), cloud cover and rain may keep things cooler over certain spots during the day. Conversely, increased cloud cover and rain during the nighttime hours may suppress radiational cooling and keep things slightly warmer overnight. For the most part, widespread Moderate HeatRisk (level 2 of 4) is expected each day. However, long range ensembles are indicating that pressure heights will increase slightly as longwave ridging shifts east and the cut off low dissolves. This will result in warmer temperatures for the weekend, with the NWS Prototype Probabilistic HeatRisk tool showing a 40 to 50 percent chance of Major heat impacts for the east coast metro areas. && .AVIATION... (06Z TAFS) Issued at 119 AM EDT Mon May 18 2026 Breezy easterly winds will continue with SHRA coverage forecast to increase once again along the east coast of South Florida between 10-12z Monday before activity pushes inland by 17-19z. Wind gusts will rise up to 20-25 kts as well. At KAPF, SHRA/TS coverage will occur after 18-19Z. && .MARINE... Issued at 119 AM EDT Mon May 18 2026 A moderate to fresh easterly breeze will remain established across the local waters early this week. Scattered showers and storms will be possible each day with extra activity expected for the Gulf waters compared to the Atlantic waters. Periods of rough seas and gustier winds are expected in and around thunderstorm activity. Atlantic seas early this week are expected generally at 3-4 feet with Gulf seas of 2 feet or less. && .BEACHES... Issued at 119 AM EDT Mon May 18 2026 A high risk for rip currents continues for all of the Atlantic beaches early this week as breezy onshore winds persist. && .PRELIMINARY POINT TEMPS/POPS... Miami 87 78 87 77 / 30 30 40 20 West Kendall 88 75 89 74 / 40 30 50 10 Opa-Locka 88 77 88 77 / 30 30 40 20 Homestead 87 77 88 77 / 30 40 40 20 Fort Lauderdale 86 78 86 78 / 30 40 40 30 N Ft Lauderdale 85 77 85 77 / 30 40 30 20 Pembroke Pines 89 78 90 78 / 30 30 30 20 West Palm Beach 86 77 86 77 / 30 40 30 10 Boca Raton 86 78 86 78 / 20 40 30 20 Naples 92 74 92 74 / 70 20 90 10 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through Tuesday evening for FLZ168-172-173. AM...None. GM...None. && $$ SHORT TERM...Redman LONG TERM....NMP AVIATION...Redman  888 FXUS63 KDLH 180806 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 306 AM CDT Mon May 18 2026 .KEY MESSAGES... - Another round of strong to severe storms Monday with timing most likely being overnight once again. Threats are hail, winds, and tornadoes. Heavy rainfall leading to localized flooding will also be possible. - Colder air returns Tuesday and Wednesday, a Freeze Warning may be needed for Tuesday night. - Next chance for precipitation will be this weekend. && .UPDATE... Issued at 246 AM CDT Mon May 18 2026 Early this morning, the initial wave of storms moving through the Northland has weakened and these storms are no longer expected to be severe. However, general showers and standard thunderstorms will continue rolling through the region into the mid to late morning hours. As we head into this afternoon and evening, another round of showers and storms is possible, primarily focusing on the northwest Wisconsin area. Cloud cover and cooler temperatures are expected to keep a firm inversion in place for most of the area. This inversion will heavily limit the potential for tornadoes north of where the environment destabilizes, mainly across central Wisconsin. The potential for large hail and damaging winds remains a threat with the strongest storms. Additionally, flooding still remains a concern due to the potential for training storms along the cold front. Fortunately, the front seems to move fast enough that any flooding issues will remain isolated. && .DISCUSSION... Issued at 224 PM CDT Sun May 17 2026 Current Conditions/Today: Strong easterly flow envelops the region today with cloud cover increasing. Radar shows areas of weak echoes across western MN and NW WI. Reports thus far have not yielded much in way of rainfall yet and will likely still take some time for this rain to make it to the surface. Especially with how dry the morning sounding was for INL. We are seeing some noticeable areas of isentropic ascent ahead of the approaching warm front though. These surges are over both the Red River Valley and into NW WI which will likely be our best chances for this initial batch of rain before the main system ramps up later tonight. That being said rain chances through the afternoon are 20-30%. Tonight: The main show is expected to arrive later tonight. An inverted trough moving across the Northern Plains will transition into the primary low pressure system with a strong cold front trailing into the Central Plains. Severe storms are expected to develop in SW SD this afternoon. Through the evening hours the low pressure will advance NE towards NW WI. A strong low level jet will help to sustain the ongoing convection and drive the activity into the Northland. Storm mode as it moves into our region will be linear with damaging winds being the primary hazard. Large hail can't be ruled out as well but the more favorable lapse rates don't line up well with the current progression of the storms. Tornado threat also looks low as surface based convection tied to the cold front looks to stay south of the region. Overall timing for the worst conditions look to move in after 9PM and exit to the east after 4AM. Primary impact areas align with where SPC has their severe weather outlook. Clipping the Brainerd Lakes area with NW WI mostly likely seeing the lion's share of the activity. Rain totals with the main band of storms could range from 0.50-1.00" with PWATs over 1.25" some storms could produce totals over 1.50" Monday: Monday's set up will heavily depend on the progression of the previous nights frontal boundary. The 12Z suite of deterministic guidance is in decent agreement with stalling out the frontal boundary over NW WI. SPC severe outlook has the marginal risk draped across NW WI and sliding southwest into southern MN. This outline essentially highlights the most likely warm sector in which we have potential for the atmosphere to reload on instability for strong to severe storms once again. Areas west of this could still see some rain development as a mid level trough pivots across the Northern Plains, but thunderstorm potential is not as great. High res guidance is once again suggesting a late night threat with linear storm mode. With the cold front being much closer to the region some storms may become tied to the surface allowing for some surface vorticity ingestion. All modes of severe will be in play with QLCS tornadoes not out of the question. Activity may ramp up as early as 7PM with some discrete cells forming in the warm sector initially. The linear storm is currently projected to move in after 9PM and out of the region by 3AM with some lingering showers. Additionally, localized flooding may become a concern. Heavy rainfall rates may impact areas already inundated from the previous round of storms. Tuesday/Wednesday: High pressure will start to move in from the west on Tuesday with highs in the 40s and 50s. Remnant moisture from the departing system with cyclonic flow aloft could still lead to some scattered showers. Tuesday night will sport some very chilly temperatures with a Freezing Warning likely being needed for most of the Northland. Temperatures rebound a bit on Wednesday as surface high pressure saunters off to the east. Highs will climb back into the 50s and 60s. End of the Work Week: With the departure of high pressure Thursday will see southerly flow returning to the Northland. Highs continue to trend back up with widespread afternoon temps expected to reach the 60s. Cluster analysis shows an upper level trough moving out of the Rockies once again which will prompt increased chances for precipitation. At this time we are carrying 20-30% chance of rain to end the week. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1222 AM CDT Mon May 18 2026 Blend of IFR and VFR for now with east winds decreasing and eventually turning light north. A complex of storms will move NW WI this morning. Thinking KHYR will be the most impacted though believe there will be the typical spring return flow that brings LIFR conditions into KDLH in the post-complex air mass with onshore easterly flow. Thinking this will last into tomorrow morning with low confidence on its occurrence due to the complex mainly dissolving in the dry air mass, so it may just act to saturate the lower levels - maybe enough to form the low stratus and fog. Another round of storms is expected this evening. && .MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 246 AM CDT Mon May 18 2026 Small Craft Advisories remain in effect for the nearshore waters this morning due to elevated northeast winds and waves. Northeast winds will ramp up again late tonight, bringing gusts up to 25 knots and building waves to 4 to 8 feet. Winds will eventually shift to the northwest by Tuesday afternoon, allowing waves to gradually subside. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .FIRE WEATHER... Issued at 246 AM CDT Mon May 18 2026 Scattered rain showers and thunderstorms will limit fire weather concerns through the early part of the week. A high pressure returns for the mid week and low minimum RHs in the 30s return once again. Gusty winds will subside briefly during the day today, but will increase once again out of the north to northwest overnight. These winds will continue into Tuesday, with sustained winds to 15 mph and gusts to 25 mph. See the Fire Weather Forecast product for a more thorough breakdown of fire weather conditions. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...Small Craft Advisory until 10 AM CDT this morning for LSZ140>148-150. && $$ UPDATE...KML DISCUSSION...Britt AVIATION...Wolfe MARINE...KML FIRE WEATHER...KML  987 FXUS63 KSGF 180807 AFDSGF Area Forecast Discussion National Weather Service Springfield MO 307 AM CDT Mon May 18 2026 .KEY MESSAGES... - A Moderate Risk (3 out of 4) for repeated rounds of thunderstorms and heavy rainfall that may result in flash flooding this morning into the afternoon. Increasing confidence in a thunderstorm complex stalling into west central and central MO. A Flood Watch in effect for an area north of Interstate 44 towards the Highway 54 corridor. - A Slight Risk (2 out of 5) for a few strong to severe thunderstorms this morning into the afternoon. Primary hazard is damaging wind gusts. - A Slight Risk (2 out of 5) for severe thunderstorms overnight tonight into Tuesday. A line of thunderstorms expected to quickly move through the area, with the primary hazard being damaging wind gusts. - Additional rainfall chances (30-50%) mid to late week along with cooler temperatures. && .SHORT TERM /THIS MORNING THROUGH TUESDAY MORNING/... Issued at 300 AM CDT Mon May 18 2026 This Morning-This Afternoon: A thunderstorm complex is gradually sliding southeast this morning across portions of eastern KS and northwest MO. This complex has become outflow dominant in nature, with any severe potential limited to damaging wind gusts at this point. This complex is expected to continue to sink southeast into portions of west central and central MO by early this morning/near sunrise. The environment becomes less favorable for organized thunderstorms given the lack of sufficient wind shear into this area. However, there may be just enough (20 to 30 knots deep- layer) in the vicinity of MUCAPE (1500 to 2000 J/kg) to support a few strong to severe thunderstorm segments. Much of the activity becomes elevated in nature this morning. The primary risk would be damaging wind gusts up to 60 mph. SPC has a Marginal (1 of 5) to Slight (2 of 5) to capture this severe potential. Expectations are for this complex to stall by mid- morning in the general area north of Interstate 44 towards the Highway 54 corridor. This will be key to a rapidly increasing concern for heavy rainfall and flash flooding that will be discussed in more detail below. An additional severe potential occurs late this morning into the afternoon with redevelopment as a low- level jet persists over the area. CAMs depict scattered thunderstorms rapidly developing across southern MO and lifting towards the stalling complex. Confidence in this scattered development is low to medium given the strong CIN to the south. Nonetheless, any activity that does develop will pose the potential hazards may include hail to the size of quarters and damaging wind gusts up to 60 mph. It is plausible some locations remain dry through this morning and afternoon across far southern MO, with PoPs 60-90% along and north of Interstate 44, falling off to 10-30% along the MO/AR border. Overall, there is still some subtle uncertainties remaining on how the mesoscale unfolds this morning and afternoon, and the true extent of the associated severe potential. As for the heavy rainfall and flash flooding potential, the attention is focused on the complex stalling into west central and central MO this morning. This environment is increasingly favorable for heavy rainfall to occur, with the complex slowing into this area thanks to very weak steering flow as seen with Corfidi vectors becoming west to east oriented at 5 knots or less. As moisture (PWATs 1.5 to 1.8 inches) continues to advect into the area, efficient rainfall rates are likely as repeated showers and thunderstorms occur over the same areas this morning into the afternoon. Guidance has trended into widespread agreement on this heavy rainfall, further increasing our confidence in heavy rainfall that will likely result in some areas of flash flooding today. The latest HREF Localized Probability Matched-Mean (LPMM) depicts a widespread corridor of 1 to 3 inches along Highway 54, with localized amounts approaching 4 to 6 inches. Given this trend and increasing confidence, a Flood Watch has been issued for portions of west central and central MO. This watch begins at 7 am this morning and runs through this evening. Further expansion in time and space may be warranted if needed. WPC has captured this heavy rainfall/flash flooding potential with an upgrade to a Moderate Excessive Rainfall Outlook (3 out of 4). There is some lingering uncertainty on how long this activity festers across the area into the afternoon/early evening, that will be best captured with trends through this morning. Tonight-Tuesday Morning: As we progress into tonight, the low-level jet will strengthen again as lift increases. Widespread severe thunderstorms are expected to develop across central/eastern KS and quickly grow upscale into a line of thunderstorms. Ensembles continue to depict the strongest lift and wind shear are focused north and west of the area where Enhanced to Moderate Severe Outlooks are present. Further to the southeast into our area, a Slight Risk (2 out of 5) is draped through the area. The most likely scenario is for the line of thunderstorms to gradually weaken as it pushes into southeast KS and west central MO overnight tonight. However, we do not want to downplay the uncertainty in the mesoscale, as just a bit more shear and instability may further fuel strong to severe thunderstorms in our area overnight into Tuesday morning. Primary hazard is damaging wind gusts up to 60 mph. Additional hazards may include large hail up to the size of quarters and a brief tornado, though these are more focused across the north and western portions of the area as line enters the area overnight. The current speed of the front and associated line moving through the area are expected to be quick, with the front potentially clearing the area by mid Tuesday morning. If this quick moving scenario plays out, any severe potential on Tuesday afternoon would be nullified. Additionally, a progressive front would limit the potential for heavy rainfall and flash flooding. Overall, it is expected to be an active next 24 to 36 hours, with some lingering uncertainties in the mesoscale. Confidence has increased in the heavy rainfall and flash flooding this morning into the afternoon, in additional to a few scattered strong to severe thunderstorms. Highs today reach into the lower to middle 80s, with dewpoints making it feel quite muggy in the upper 60s to near 70. Gusty southerly winds around 25 to 35 mph persist through today and tonight. By late tonight into early Tuesday morning, attention turns towards the quick moving line of thunderstorms with an additional severe potential. Continue to follow the forecast for updates. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 300 AM CDT Mon May 18 2026 Remainder of Tuesday: Behind the frontal passage, winds will turn out of northwest as cooler air gradually funnels into the region. Lows Tuesday night fall into the 50s to near 60. Wednesday-Thursday: Ensemble guidance suggests low rain chances (20-50%) lingering post- frontal into Wednesday, particularly across southern MO. Meanwhile, cooler temperatures prevail on Wednesday with highs topping out in the upper 60s. This pattern persists into Thursday, with additional rain chances (20-50%) into Thursday afternoon and night. Temperatures will gradually be on the rebound with subtle mid- level height rises. Next Weekend: The general pattern remains southwesterly flow, with additional shortwaves tracking through the region into next weekend. There is uncertainty on the exact timing and strength of these waves,that will be better resolved over the coming days. Nonetheless, carrying additional rain chances into next weekend. A warming trend returns into next weekend as well. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1233 AM CDT Mon May 18 2026 Southerly flow will continue to bring gusty surface winds to the region through the overnight hours and during the day Monday. Along with the winds will come increasing moisture which will bring increasing low level clouds with VFR to MVFR ceilings over night. A band of showers and storms located across eastern Kansas into northwestern Missouri will begin to move to the south overnight. This band is expected to make its way into the northern Ozarks and bring the potential for showers and storms. Where storms occur, impacts to visibilities and ceilings will occur. && .CLIMATE... Issued at 200 PM CDT Sun May 17 2026 Record High Temperatures: May 18: KSGF: 88/1962 KJLN: 90/1987 KVIH: 88/1996 KUNO: 89/2001 Record Warmest Low Temperatures: May 18: KSGF: 68/1996 KJLN: 74/1996 KUNO: 66/2017 KVIH: 70/1996 May 19: KSGF: 69/2013 KJLN: 74/1996 KUNO: 70/1996 KVIH: 70/1996 && .SGF WATCHES/WARNINGS/ADVISORIES... KS...None. MO...Flood Watch from 7 AM CDT this morning through this evening for MOZ055>058-066>071-078>081. && $$ SHORT TERM...Perez LONG TERM...Perez AVIATION...Hatch CLIMATE...Burchfield  046 FXUS63 KFSD 180808 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 308 AM CDT Mon May 18 2026 .KEY MESSAGES... - Scattered showers and isolated thunderstorms return to the area by early this afternoon, continuing through this evening into tonight. - A few storms along and southeast of a Wayne to Sheldon to Windom line may be strong to severe late this afternoon into this evening. Confidence in this risk is low. - Cool conditions prevail this week. Dry weather expected mid week. Another round of storms is possible Thursday through Friday. && .UPDATE... Issued at 304 AM CDT Mon May 18 2026 Temperatures this morning range from the mid 40s to the mid 60s from west to east. Lows tonight fall to the upper 30s to mid 50s, although areas west of the James River may stay a bit warmer than the upper 30s if stratus lingers longer into the overnight hours, as some models hint at. Still seeing breezy winds with gusts to 30 mph at times. Focus shifts to the next wave progged to move out of the Rockies late this afternoon through tonight, as well as the preceding WAA and weak vorticity lobe. Expect scattered showers and isolated thunderstorms to develop this morning across NE and lift northward into our area by the afternoon hours. Showers and isolated storms continue through the evening/overnight hours, tapering down from west to east as the 700mb trough moves across the area. A few isolated strong to severe storms are possible along and southeast of a line from Wayne to Sheldon to Windom, mainly from 4 to 9 PM. Confidence is low in the chances for severe weather, as there are a few questions. One, how much do skies clear during the day, especially with latest guidance showing stratus remaining in place through the early afternoon? Two, depending on cloud cover, how much can the atmosphere recover from yesterday's storms? Finally, where do any boundaries end up today, and how quickly does the elevated front move east? If we are able to get a stronger storm or two to develop, hail to ping pong ball size (1.5") and wind gusts to 60 mph are the main threats. If we have a surface boundary or get a surface based storm (more likely if we're able to clear out today), a tornado cannot be ruled out, although risk is low. Heavy rain in thunderstorms may cause some localized flooding issues if storms track over the same areas which received heavy rain over the weekend. Stay aware for possible warnings later today. && .DISCUSSION... Issued at 120 PM CDT Sun May 17 2026 The short-term convective outlook presents a highly volatile spring severe weather setup. Latest surface analysis shows a complex pattern, anchored by a strong 994 mb low over northwest KS. An inverted trough extended north of the low through central SD, while a well-defined warm front stretched northeast of the low into east central NE. A weaker low was also noted in north central NE. Visible satellite imagery revealed stable wave clouds advancing northeast over far northeast NE and extreme SE SD, ahead of the advancing warm front. Regional radar imagery showed a complex of strong to severe storms over north central NE. This storm complex is forecast by short range guidance to continue tracking east this afternoon, intensifying as interacts with the richer low- level moisture pool near and south of the warm front. Moderate to strong instability will be in place over the southern to eastern CWA by late afternoon with MLCAPE nearing 3000 J/kg. In addition, deep layer shear will increase to around 50 kt, coincident with a mid level speed max ejecting from the deep upper trough to our west. As the system evolves over the next several hours, it appears the ingredients for a significant severe weather event will be most favored over the southern to eastern CWA. Ahead of the main convective line, some CAMs show supercell development along the northward advancing warm front. These storms would present a risk of very large hail (2"+) and tornadoes. Given the amount of low level SRH/curved hodographs present, a couple strong tornadoes are possible. The convective cluster currently entering our far southwest CWA should strengthen as it shifts east, with an initial hail and tornado threat transitioning to a damaging straight line wind threat (70+ MPH) as it grows upscale into a squall line/QLCS. Some line-embedded QLCS tornadoes are possible, especially for any line segments that become oriented north/south or northwest/southeast, given southwesterly 0-3 km shear vectors. Timing from latest high-res guidance suggests this activity exits to the east of our CWA late this evening. Precipitation amounts will vary significantly based on convective tracks, though NBM guidance and HREF probability match mean fields project a widespread 0.50 to 1.50 inches of rainfall, particularly across northwest Iowa and southwest Minnesota. On Monday, the cold front finally pushes into the area. Instability and shear are forecast to be much lower than today, however, there will be a conditional risk of severe storms over the eastern CWA during the late afternoon to evening, if the airmass can destabilize sufficiently ahead of the front. SPC's Day 2 outlook indicates as Marginal Risk (level 1 of 5), for our MN and IA counties. Behind the departing upper wave, quasi-zonal flow sets up for Tuesday and Wednesday, yielding quiet conditions and seasonally cool high temperatures moderating from the upper 50s Tuesday to mid-upper 60s Wednesday. The next upper wave moves in for the Thursday to Friday period, however Gulf moisture remains cutoff ahead of this system. Evaluating the ECMWF Extreme Forecast Index (EFI) reveals no significant climatological anomalies for precipitation or wind across the upper Midwest during this period, reinforcing the the idea of a low-impact system for our area. The current forecast sticks closely to the NBM consensus, maintaining broad 20-30 percent probabilities for light rain for late Thursday into Saturday. By late this week and especially this weekend, temperatures will embark on a steady upward trajectory, as the mid level flow backs west, then southwest. The Climate Prediction Center (CPC) 6-10 day outlook favors above-normal temperatures across the Northern Plains and Upper Midwest, which supports blended guidance high temperatures reaching well into the 80s on Sunday. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1247 AM CDT Mon May 18 2026 A mix of VFR down to LIFR across the region as low stratus persists through most of the period. Breezy northwest winds gusting 20-25 kts west of I-29 will also prevail for the period. To the east gusts are west becoming northwest at 10-15 kts. Monday morning winds become northerly and increase through the afternoon and into the evening. Peak gusts of 25-35 kts are expected, with the strongest winds over south central South Dakota. The stronger winds gradually progress to the east toward the end of the period. Dry conditions are expected until Monday afternoon. Chances for showers and thunderstorms increase through the afternoon and into the evening. Showers will be scattered in nature and will be more periodic than continuous. As we approach the late afternoon and early evening, severe risks increase especially for areas of northeast Nebraska and northwest Iowa. There is some question on how well the atmosphere will recover before Monday afternoon. This may limit severe potential to just a few storms. Stronger storms that do form may be capable of producing large hail and damaging wind gusts. Showers and storms continue through the end of the period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ UPDATE...SG DISCUSSION...ILX/25 AVIATION...AJP  600 FXUS63 KICT 180812 AFDICT Area Forecast Discussion National Weather Service Wichita KS 312 AM CDT Mon May 18 2026 .KEY MESSAGES... - Scattered to numerous thunderstorms this afternoon through overnight. All severe weather hazards possible, including large hail, damaging winds, a few tornadoes, and heavy rainfall. Greatest chances for severe weather will be over central KS. - Warm and windy today, with cooler weather tonight through Thursday. - Periodic on-and-off shower/thunderstorm chances Wednesday night through the weekend. A few bouts of strong to severe storms along with heavy rainfall are possible, but widespread severe weather potential appears low at this time. && .DISCUSSION... Issued at 305 AM CDT Mon May 18 2026 THUNDERSTORM CHANCES: PREDAWN HOURS--THIS MORNING...Remnant outflow boundary from current central-northeast KS thunderstorm complex is expected to lay out generally along the Highway 50 to Highway 54 corridor through this morning, before retreating back northward this afternoon. A strong low-level jet impinging on this boundary should support continued festering showers/thunderstorms across central and east-central KS during the predawn hours, shifting east into east-central KS and western Missouri this morning. Really like the HRRR's depiction of this activity, which keeps it mostly north of Highway 54. Thinking the primary concerns will be marginally severe hail (at worst) and areas of heavy rain and associated flooding concerns. MID-LATE THIS AFTERNOON--TONIGHT...Otherwise, attention then turns to this afternoon-evening, when a sharp dryline/cold front combo ahead of an ejecting shortwave trough will be the focus for scattered to numerous thunderstorm development. Thinking initiation will occur by 3-4pm over central KS, with storms expanding in coverage and spreading south-southeast during the evening and overnight. Further south, can't rule out an isolated dryline storm over south-central KS, but thinking those chances are lower given slightly more capping and weaker forcing. Strong to extreme fat instability coupled with 35-45 kts of deep layer shear oriented mostly parallel to the boundary should support a rather messy storm mode, with clusters of supercells early on gradually transitioning to linear with embedded supercell structures with time. Very large hail and damaging winds will be the primary threats before about 7-8pm, along with the potential for a few supercell tornadoes given strengthening low-level shear. Reason- being, it's during this time (i.e. 3-8pm) storms will have the greatest chance of being discrete or semi-discrete. Additionally, we could also see a handful of landspout tornadoes during this time across mainly central KS, given the expected strong low-level vorticity along the slow-moving boundary combined with the extreme buoyancy. As we head past 7-8pm or so, thinking the potential for both supercell and landspout tornadoes along with very large hail should start to decrease given the likely transition to mostly linear convection as the cold front picks up steam to the southeast, with the primary threats likely being golfball size hail or less, along with a damaging wind risk as storms trudge into south-central and southeast KS Can't rule out a few brief embedded tornadic circulations within this linear activity given the very strong low- level shear, but the overall tornado threat should lessen once the transition to linear storm mode occurs. Finally, another threat with this activity will be locally very heavy rainfall and associated flooding concerns, especially over central KS before 8pm when storms have the potential to train over the same areas due to the stalled nature of the frontal zone. WEDNESDAY NIGHT--WEEKEND...Periodic on-and-off shower/thunderstorm chances are possible mid week through the weekend, as a handful of low-amplitude shortwaves traverse Mid-America amidst returning low- level moisture. Thinking there will be some opportunities for strong to severe storms and heavy rainfall during this period, although widespread severe weather appears unlikely. There's quite a bit of uncertainty surrounding this period, stay tuned. WIND: Strong south winds will continue today, as low pressure continues to deepen to the west. Sustained winds of 25-35 mph with gusts up to around 45-50 mph are likely. Will continue the inherited wind advisory from mid this morning into this evening. TEMPERATURES: Southerly flow and above average heights/thickness will support continued above average temperatures through today, with overnight lows in the 60s to low 70s and daytime highs in the 80s and 90s. A strong cold front will blast south across the region tonight, supporting near to below average temperatures Tuesday through Thursday, with daytime highs in the 60s-70s and overnight lows in the 40s-50s. Deterministic and ensemble consensus shows a warming trend from late week through next weekend and beyond. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1239 AM CDT Mon May 18 2026 A line of showers and thunderstorms continues to fester over central Kansas while propagating east and slowly diminishing. Widespread MVFR ceilings are expected to develop across much of the area with some pockets of IFR possible north of the stationary front/outflow boundary in central Kansas as we move into the predawn hours as we remain in a very moist airmass. Strong and gusty southerly winds will return to much of the area on Monday. Numerous showers and thunderstorms are also expected to develop on Monday afternoon along a sagging cold front with other storms possible along a dryline which is expected to be just west of the area. This activity is expected to develop into a line as we move into the evening hours while moving east of the area shortly after midnight. Some low clouds may redevelop in the wake of the front with breezy northwest winds also anticipated. && .ICT WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 9 AM this morning to 10 PM CDT this evening for KSZ051>053-067>070-082-083-091>094-098. && $$ DISCUSSION...ADK AVIATION...MWM  596 FXUS64 KHUN 180812 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 312 AM CDT Mon May 18 2026 ...New NEAR TERM... .KEY MESSAGES... Updated at 1030 PM CDT Sun May 17 2026 - Low chances for showers and thunderstorms mainly in northeast Alabama Monday - Low to medium chances (20-60%) for showers and thunderstorms returning late Tuesday, then medium to high chances (40-80%) for showers and thunderstorms each day, from Wednesday through next weekend && .NEAR TERM... (Today) Issued at 312 AM CDT Mon May 18 2026 No major changes since the previous forecast update. Thunderstorm chances remain low (less than 10%) throughout the day with lack of support for strong storms. Highs are forecast to be above-normal, once again, with temperatures peaking in the upper 80s to lower 90s. Breezy, southerly winds will provide some relief from the heat with gusts up to around 20 mph during the afternoon hours. Previous Discussion: For Monday, a plume of enhanced moisture on the western edge of the sub-tropical ridge will move a little further into AL, although highest moisture content is expected to be to our south. Nevertheless, a few showers/storms could develop particularly along the plume axis during peak heating in the afternoon. Vertical thermo and shear profiles are not supportive of any strong storm organization, with 0-6km bulk shear generally at or less than just 15 kts. && .SHORT TERM... (Monday night through Wednesday) Issued at 1045 PM CDT Sun May 17 2026 From Monday night into Wednesday, the broad upr ridge will continue to hold sway across the Southeast, with deep SW-W flow remaining across the TN Valley. A trough in the Intermountain West into the North/Central Plains will remain nearly steady initially, but become increasingly positively tilted and deamplify as short waves round its base and move NEWRD. Essentially, the sub-tropical ridge will maintain dominance over much of the Southeast CONUS and westward into the Southern Plains, keeping the trough from advancing. However, a low-level boundary will make inroads towards the mid-South by mid-week, while SWRLY flow along the trough/ridge interface edges closer to the area. The result will be increased instability across our area with higher dew points and added dynamic forcing by late Tuesday and into Wednesday. Shower and thunderstorm chances will increase to low/medium during this period, with better chances in NW portions of the area closer to the better forcing. With a continued lack of deep layer shear, and modest thermo profiles, the activity will be more akin to general thunderstorm activity late Tuesday into Wednesday. Increased dew points will create warmer feeling conditions overall, but increased clouds and shower activity will make for lower max temperatures during the day especially on Wednesday. && .LONG TERM... (Wednesday night through Sunday) Issued at 1045 PM CDT Sun May 17 2026 This pattern will continue largely unabated from Wednesday night into the weekend, with a broad summer-like subtropical ridge centered near Bermuda and deep SWRLY flow persisting across the TN Valley. A series of shortwaves are expected to ride along the trough/ridge interface across the region and bring bouts of increased shower/storm activity. Timing this is difficult, as the distinct nature of these shortwaves is difficult to discern in the model guidance. Nevertheless, increased instability during the daytime will certainly act to regulate chances for showers/storms during the period. Thermo profiles during the Thurs-Friday period do not appear to change significantly, with generally moist- adiabatic type profiles in the increasing deep/humid airmass. PWs climbing to near 1.7 inches and only modest CAPEs and weak-modest shear would suggest the largest threat may be due to any localized flash flooding that could result, especially with the prospect for slow-moving training storms. Shear may increase a little into the weekend, but still would characterize as modest at best. Overall, this is reminiscent of a warm, early summer pattern with highs mostly in the 80s and warm nights with lows in the 60s. && .AVIATION... (06Z TAFS) Issued at 1155 PM CDT Sun May 17 2026 VFR conditions are forecast through the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...HC SHORT TERM....KDW LONG TERM....KDW AVIATION...HC  675 FXUS65 KBYZ 180813 AFDBYZ Area Forecast Discussion...Updated National Weather Service Billings MT 213 AM MDT Mon May 18 2026 .KEY MESSAGES... - Frost/freeze this morning and Tuesday morning, coldest Tuesday morning. Make sure to protect sensitive vegetation. - Cooler and breezy with occasional chances of precipitation today. - Light snow accumulations (an inch or less) over the foothills this morning. Minor impacts to travel are possible. - Periods of light to moderate mountain snow today. Recreation could be impacted by winter conditions. - Another weather system brings the chance of precipitation Wednesday into Thursday. && .UPDATE... Have gone ahead and cancelled the Winter Weather Advisory for the Beartooth and Red Lodge foothills, as impactful snow is no longer expected. The remainder of the forecast remains in good shape. STP && .DISCUSSION... Today through Sunday... Today will be cool, breezy, and unsettled under the influence cyclonic flow aloft. With this, high temperatures will be in the 40s to lower 50s with brisk northerly wind gusts in the teens and 20s mph for most, with occasional 30s mph near the mountains and foothills. While there is at least a slight chance (15 percent or greater) of light precipitation across the area today, the best chance of more persistent precipitation is to the south near the Montana-Wyoming state line. With this, snow levels will be low enough to favor a rain and snow mix, with mostly snow during the morning hours over the foothills. This may lead to minor travel impacts for the morning commute along the Beartooth and Red Lodge foothills and the Sheridan foothills. However, accumulations are expected to remain relatively light with additional accumulations up to an inch mainly on grassy surfaces. Slick roads could also develop as temperatures drop below freezing tonight along the foothills. With that said, the Winter Weather Advisory remains in effect for the Beartooth and Red Lodge foothills to accommodate the potential for additional, potentially more robust snow shower development this morning. Precipitation gradually comes to an end late today, lingering the longest over far eastern Montana. A stray shower or two may even linger into early Tuesday morning over Fallon and Carter Counties (up to a 15 percent chance). Tuesday will be warmer with high temperatures in the 50s and 60s. While most areas will remain dry under shortwave ridging aloft, an isolated shower or two is possible over the mountains west of Billings during the afternoon (10 to 20 percent chance). Wednesday into Thursday, the chance of precipitation returns as another weather system and associated cold front move through the region. This cold front, expected to drop through the area sometime late Wednesday into early Thursday, looks to bring decent frontogenesis that could support at least scattered precipitation. With this, the chance of seeing any precipitation is currently 40 to 80 percent, greatest over south-central Montana and north-central Wyoming where upslope enhancement looks to be in play. The one potential issue to watch is that models are starting to show the system may split. If this happens, the best energy could dive south and limit the precipitation potential over our area. At this time though, models continue to provide enough frontogenesis and upslope enhancement to favor precipitation. As far as the precipitation type goes, precipitation would mostly be rain for the lower elevations and snow in the mountains with snow levels around 7000 feet. Friday into the weekend looks to remain unsettled with northwesterly flow aloft. While temperatures are currently advertised to warm back into upper 70s and 80s this weekend, temperatures may trend slightly cooler (more in the 70s) as potential weather systems moving through the northwesterly flow aloft are picked up in the models. Arends .AVIATION... Snow showers will continue to obscure the mountains at times today. Scattered rain/snow showers will impact foothill locations at times as well (KLVM and KSHR), with isolated rain showers over the plains. MVFR to local IFR conditions are possible with the showers, with more widespread MVFR ceilings overspreading the area early this morning. Look for conditions to gradually improve during the afternoon and evening with lifting ceilings and decreasing shower coverage. STP && .PRELIMINARY POINT TEMP/POPS... Tdy Tue Wed Thu Fri Sat Sun ------------------------------------------------------- BIL 050 029/067 043/071 043/063 042/071 045/079 050/084 2/W 10/U 01/B 75/T 11/B 00/B 01/B LVM 048 025/062 036/065 036/061 036/068 040/076 044/080 4/W 10/B 02/W 85/T 12/T 11/B 11/N HDN 050 026/067 037/073 041/064 039/072 042/079 047/083 2/W 10/U 01/B 65/T 22/T 10/B 01/B MLS 048 030/064 040/073 043/065 041/071 043/078 048/082 2/W 20/U 01/B 44/W 11/B 10/B 11/B 4BQ 045 029/062 038/072 043/062 040/068 043/076 048/081 5/W 20/U 00/U 26/W 22/W 10/B 01/B BHK 046 029/059 035/072 039/064 038/068 042/075 046/081 4/W 20/B 01/B 34/W 32/W 21/B 11/B SHR 043 024/060 031/067 036/058 033/067 036/075 040/080 8/W 10/U 01/U 47/T 23/T 11/B 01/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Winter Weather Advisory in effect until noon MDT today FOR ZONE 171. WY...Winter Weather Advisory in effect until noon MDT today FOR ZONE 198. && $$ weather.gov/billings  595 FXUS65 KGGW 180812 AFDGGW Area Forecast Discussion National Weather Service Glasgow MT 212 AM MDT Mon May 18 2026 .KEY MESSAGES... - Overnight temperatures tonight will be at or near freezing. - Warm weather returns mid week. The next chance for showers returns Wednesday. && .DISCUSSION... WEATHER PATTERN OVERVIEW: A strong upper trough will keep cool conditions through tonight before weakening and allowing temperatures climb closer to normal by Wednesday. Tonight low temperatures look to drop below freezing with clearing skies and light wind. With these cooler temperatures, make sure to protect sensitive vegetation. By mid week upper level ridging over the west coast will allow quick moving shortwave troughs to sneak through the overall quasi- zonal flow, bringing some isolated thunderstorm chances through the end of the weeeeek (get it? it's like a rollercoaster). The best chance for thunderstorms will be Wednesday. Model plumes continue to suggest weak instability in the ~300 J/kg MLCAPE range during Wednesday evening. GEFS forecast RH and dewpoint for Wednesday evening continue to rise. FORECAST CONFIDENCE & DEVIATIONS: No changes to NBM. && .AVIATION... LAST UPDATED: 0730Z FLIGHT CAT RANGE: MVFR, IFR through 18Z. DISCUSSION: Low overcast skies with brief, light rain showers possible through early this morning. IFR ceilings dropping as low as 500ft intermittently over KGDV and KSDY until 18Z. WINDS: North winds 10 to 15 mph through 3Z tomorrow. Light and variable thereafter. && .GGW WATCHES/WARNINGS/ADVISORIES... None. && $$ weather.gov/glasgow  796 FXPQ50 PGUM 180815 AFDGUM Area Forecast Discussion National Weather Service Tiyan GU 615 PM ChST Mon May 18 2026 .Marianas Synopsis... Mostly cloudy skies and scattered showers are forecasted for the Marianas tonight. A return to isolated showers and partly cloudy skies may continue until the weekend. Combined seas are between 6 to 8 feet, and a high risk of rip currents remains along east-facing reefs at least through Tuesday afternoon. && .Discussion... Satellite and model trends show low-end scattered showers as the trade-wind surge and surface troughs continue to produce showers moving downstream towards the Marianas, so Probability of Precipitation (PoPs) values will remain at 30 percent for the entire region tonight. Isolated showers are expected to remain through the rest of the week, but moisture trends will continue to be monitored as the troughs south of Wake Island progress downstream over the next several days. Scatterometry shows some pockets of elevated trade winds over open waters to the far east, but models (validated by today's observations) indicate winds remaining 15 to 20 miles per hour with gusts up to 25 miles per hour for the region until the latter half of the week when the trades potentially downtrend through the weekend. A slight chance of thunderstorms is introduced in the last few periods of the forecast, but confidence is low as models struggle to agree on the source, whether it be a weak trough or a potential disturbance passing south of Guam. Regardless, this will continue to be monitored and communicated as the week progresses. && .Marine... Buoy and altimetry data indicated combined seas of 6 to 8 feet across the region and is expected to continue until midweek when sea heights may drop a foot or two through the rest of the week. The easterly trade winds are expected to remain moderate to fresh through the rest of the week before potentially dropping to just moderate over the weekend. Surf will remain at 9 feet tonight along east-facing reefs, so a high risk of rip currents remains at least through Tuesday afternoon. Surf conditions will continue to be monitored as the rip current risk will need to be re-evaluated tomorrow afternoon. && .Tropical Systems... A weak subtropical disturbance on the northwestern edge of Guam's Area of Responsibility (AOR), centered near 22N131E, has been dubbed Invest 98W by the Joint Typhoon Warning Center. 98W exists on the southwestern edge of a decaying stationary frontal boundary to the east of Taiwan, which extends east-northeast to a low-pressure system well beyond 25N137E. Numerous showers and scattered thunderstorms are seen within the moist convergent flow wrapping into 98W along its eastern flank, just south of the nearly-dissipated baroclinic zone extending from it. Invest 98W looks to remain within the region only briefly, with model guidance depicting a north to north-northwest movement along 130E, exiting north and west of the AOR by late Tuesday morning. 98W then looks to merge with an eastward-propagating mid-latitude system around midweek. && .Eastern Micronesia... A disorganized, unsettled pattern continues across the region. Pohnpei saw numerous showers and isolated thunderstorms throughout the morning hours, due to strong convergence along a nearby trade- wind trough. This was supported by an area of divergence aloft, associated with a broad upper-level low centered well northeast of Pohnpei, to the south of Wake Island. Himawari visible satellite this afternoon shows lingering widespread cloud cover across Pohnpei State, with patchy stratiform showers nearby. Much drier conditions prevail over Kosrae and Majuro, with most of the showers focused well to the north of Kosrae, and over the northeastern Marshall Islands. Numerous showers are also seen to the southwest of Kosrae, near and south of the Equator, associated with an Intertropical Convergence Zone (ITCZ) fragment over far southern Pohnpei State. The upper-level low to the south of Wake Island looks to shift slightly westward over the next day or so as it extends toward the west-southwest. The change in orientation of the low, in addition to the development of an upper-level high to its west near the Marianas, looks to focus strong upper-level divergence over Chuuk and Pohnpei States over the next few days. This looks to interact with a trough and convergence boundary at the surface, to support numerous showers and isolated thunderstorms for Pohnpei around Tuesday and Tuesday night. The upper-level low looks to gradually open into a trough, which will linger and weaken throughout the rest of the week. Model guidance indicates an unsettled pattern will continue through the week, with numerous to widespread showers focusing farther to the west, mainly over central Micronesia. Meanwhile, an ITCZ looks to develop near the Marshalls by the end of the week, with a series of weak troughs propagating westward along it. These features will maintain a wet pattern across the region, with at least scattered showers expected into the end of the week for all three forecast points. Benign marine conditions are expected through the week. Latest altimetry data indicates combined seas between 5 and 7 feet across much of the region. Models depict a gradual relaxation of the east to northeast trade swell throughout the week, allowing seas to diminish by a foot or two over the next several days. && .Western Micronesia... The main weather makers for the region are a band of convergence between Chuuk and Pohnpei, a second band of convergence near Yap Proper, and a trough over southern Palau. Over southern Palau, an east-to-west oriented trough has set up and is producing scattered showers. Model guidance suggests this trough will move through the region over the next day or so. Looking further out, a trade-wind regime is expected to return through next week. Near Yap, the convergence band is interacting with a subtle trough and is producing scattered showers that is expected to build into widspread showers with isolated thunderstorms over the evening and early morning hours. This interaction is anticipated to remain in the Yap Proper area for a day or two. Then, a series of troughs is expected to pass through the beginning of next week, anticipated to bring scattered showers to Yap. Meanwhile in Chuuk, satellite imagery shows trade-wind convergence showers to the south of Weno. Showers are expected to build into Chuuk's coastal waters overnight. Then over the week, the showers and troughs that are affecting Pohnpei now are expected to move into Weno making for a fairly wet week. Benign marine conditions are expected to continue through much of the upcoming week. Altimetry shows 2 to 4 foot seas at Palau and Yap, and 4 to 6 feet at Chuuk. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...High Rip Current Risk through Tuesday afternoon for GUZ001. MP...High Rip Current Risk through Tuesday afternoon for MPZ001>003. Marianas Waters...None. && $$ Marianas: Mesa East Micronesia: DeCou West Micronesia: Bowsher  699 FXUS61 KCLE 180814 AFDCLE Area Forecast Discussion National Weather Service Cleveland OH 414 AM EDT Mon May 18 2026 .WHAT HAS CHANGED... Trended high temperatures up a degree or two for today and Tuesday in central and eastern portions of the area. The Marginal Risk for Severe Thunderstorms has been expanded across northern Ohio into Northwest Pennsylvania for this evening. && .KEY MESSAGES... 1) The hottest temperatures of the year arrive today and continue on Tuesday. The heat will break behind a cold front on Wednesday with below normal temperatures continuing into Thursday. 2) A few strong to severe thunderstorms are possible in Northwest Ohio and across the northern counties this afternoon and evening. The potential for severe thunderstorms returns on Tuesday afternoon with greater coverage of storms expected. Damaging wind gusts to 60 mph and hail are the primary concerns with severe thunderstorms. 3) Unsettled conditions are expected heading into the holiday weekend. && .DISCUSSION... KEY MESSAGE 1... The local area resides in the warm sector today with a ridge over the Appalachians and 500mb heights of 585dm. A southwesterly pressure gradient supports warm advection with 925mb temperatures reaching 24-25C. Winds are expected to gust to 20-25 mph in the east and up to 30 mph in the west which will help to mix out dewpoints and keep humidity/heat index values in check. The high temperature forecast was raised by 1-3 degrees from north central Ohio into Northwest Pennsylvania for this afternoon with highs expected in the upper 80s to near 90 degrees and heat index values only running about a degree higher. With that said, this is the first near 90 degree day of the season and people will likely feel the effects of heat more easily. Several climate sites are forecast to be within a degree or two of record values(see the climate section below). The temperature forecast for Tuesday is a little more tricky as we have to contend with increasing cloud cover and higher chances of precipitation during the afternoon. Dewpoints also trend up closer to the mid 60s so humidity will be more noticeable. Due to the increasing clouds and moisture, temperatures will likely top out a couple degrees lower than Monday but heat index will be virtually the same. The brief bout of near record highs will abruptly end on Wednesday behind a strong cold front. 850mb temperatures fall by 11-12C in 24 hours with a northwesterly flow off the lake. High temperatures are forecast to be 20-25 degrees cooler by Wednesday and remain cool on Thursday. Temperatures do gradually trend warmer heading into the holiday weekend but will be impacted by chances for precipitation. KEY MESSAGE 2... Convection is ongoing this morning from the Upper Peninsula of Michigan extending southwest to Iowa ahead of low pressure located over western Wisconsin. A moist and unstable airmass advances eastward into the Central Great Lakes today as the trough over the Great Basin shifts east into the Plains states. Leading shortwave energy across northern Wisconsin tends to weaken while another shortwave is expected to move across Indiana and western Ohio later today. While we start the day capped, mixed layer CAPE of 800-1100 may sneak into northwest Ohio late this afternoon ahead of the shortwave which comes with increasing shear values. The better lift skirts Lake Erie and the lakeshore counties into this evening and may have to monitor for a few stronger storms moving east from Toledo towards Erie in the 4-9 PM window. While activity is generally expected to dissipate for the overnight hours, a moist and weakly unstable airmass resides overhead tonight so kept a low pop in the forecast through Tuesday morning. On Tuesday surface low pressure is forecastto move northeast across Lake Superior with a cold front extending south through the Central Great Lakes. A pre-frontal trough with moderate instability moves into NW Ohio during the afternoon on Tuesday. Expecting good coverage of showers and thunderstorms to develop west of the I-71 corridor during the afternoon with around 2000 J/kg of ML CAPE and 20-30 knots of bulk shear. Thunderstorms will continue eastward through the evening. This looks to present a scattered wind and hail threat for Tuesday afternoon and evening from about 2-10 PM. Storm relative helicity values are slightly higher in the northeast with good veering of the flow with height and the Storm Prediction Center has included a low end tornado threat for that area. Rain will linger along the cold front Tuesday night into early Wednesday with a drying trend through the day on Wednesday as broad high pressure expands south of Lake Erie. KEY MESSAGE 3... Confidence in pattern evolution is low heading into the upcoming holiday weekend. Models depict southwesterly flow and moisture advection later Friday into Saturday ahead of a trough approaching from the Plains and a ridge along the East Coast. This will likely result in an unsettled pattern with periods of showers and thunderstorms. Timing is difficult this far out but could see the first round of precipitation Friday night into Saturday then additional precipitation possible later in the day on Sunday. && .AVIATION /06Z Monday THROUGH Friday/... Mainly VFR expected for the TAF period, but with some convective potential. Convection will likely develop to the west this afternoon and spread towards TOL and FDY early this evening before weakening. Have a window of VCTS with a TEMPO for more significant restrictions at TOL and FDY early this evening. Some hints of isolated convection firing near YNG early this evening as well, though with lower confidence, so handled with VCSH. Outside of convective potential, afternoon cumulus will likely produce a SCT sky around 040-050 at times today. Winds are generally 5-10kt out of the south early this morning. Maintain some low-level wind shear at TOL and FDY with a roughly 40kt low-level jet overhead and a near-surface inversion early this morning. Winds will shift south-southwest and increase to 12-18kt with gusts to around 25kt late this morning into this afternoon. Thunderstorms may produce higher gusts at TOL/FDY. Outlook...Non-VFR possible in showers and thunderstorms at western terminals Monday night. Non-VFR likely at times in showers/thunderstorms Tuesday into Wednesday. Non-VFR possible in showers on Friday. && .MARINE... South winds are slightly elevated at 10-15kt early this morning and will continue today. Gusts up to 25kt are possible in the nearshore waters west of Cleveland this afternoon. Thunderstorms may reach western Lake Erie this evening, and could pack brief wind gusts over 35kt before dissipating while tracking east. Otherwise, southerly winds will remain slightly elevated at 10-15kt tonight into Tuesday. Winds increase a bit further to 15-20kt Tuesday afternoon, with gusts potentially up to 30kt in the nearshore waters west of Cleveland. Small craft headlines remain possible for Tuesday. There is additional thunderstorm potential spreading from west to east Tuesday afternoon and evening along and ahead of a cold front, again with potential for storms over the lake to pack strong wind gusts over 35kt. Winds whip around to the north late Tuesday night into Wednesday behind the cold front, and gradually shift more northeasterly Wednesday into Thursday and more easterly for Friday. These winds are currently forecast to be around 15kt which would bring choppiness, but there is a chance winds trend up closer to 20kt Thursday into Friday, which could warrant somesmall craft/beach hazards headlines. && .CLIMATE... High temperatures today and Tuesday will approach record values. The following are the records for May 18 and 19 at local climate sites. Date Toledo Mansfield Cleveland Akron Youngstown Erie 05-18 95(1962) 92(1962) 91(1962) 92(1962) 92(1962) 89(1889) 05-19 92(1996) 88(1964) 88(1998) 91(1911) 89(1934) 90(1996) && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ DISCUSSION...10 AVIATION...Sullivan MARINE...Sullivan  125 FXUS63 KMPX 180823 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 323 AM CDT Mon May 18 2026 .KEY MESSAGES... - Another round of showers & thunderstorms tonight. Can't rule out a few strong to severe storms from far-southern Minnesota into western Wisconsin. -Seasonably cool & dry midweek. Rain chances return Friday. && .DISCUSSION... Issued at 253 AM CDT Mon May 18 2026 A few remnants showers & thunderstorms will linger over the area towards sunrise, but all of the active weather has moved well off to our east overnight. Cloud cover is expected to stick around through much of the day today, & cool northeast winds mean that temperatures may struggle to warm much out of the 50s & low 60s across much of central Minnesota. Farther east, portions of western Wisconsin will still remain ahead of the surface low/cold front & temperatures could reach the 70s this afternoon along with muggier dew points in the 60s. We'll stay dry for much of the day today, but another round of showers thunderstorms is expected to spread northeastwards out of the central plains this evening. We should north of the prime environment for severe weather across KS/NE/IA, but will have to watch just how far north a corridor of weaker surface- based instability can make it into far-southern Minnesota & western Wisconsin this evening. Expect scattered showers to quickly spread northwards across MN & WI during the early evening, with the heaviest rainfall & best chance for thunder coming between8 PM to midnight. Can't rule out a few strong to severe storms capable of damaging wind gusts across these areas, but otherwise we're just expecting your typical spring showers with a few rumbles of thunder at time. The most widespread concentration of thunderstorms, & heaviest rainfall amounts, are expected from southern Minnesota into west-central Wisconsin where rainfall amounts of 1-2" are likely. Elsewhere, the showers will be lighter & more sporadic so only expecting rainfall amounts on the order of 0.25-0.5". The showers & thunderstorms will continue on & off through the night, ending from west to east around sunrise. Much cooler weather arrives after the rain with temperatures struggling to warm out of the 50s Tuesday. Strong cyclonic flow & colder temperatures aloft will likely create a prime environment for isolated diurnally-driven showers during the afternoon, but rainfall amounts from these will be light. May need to monitor the potential for another frost/freeze Wednesday morning if clouds are able to clear out overnight & the radiational cooling potential is maximized. Seasonably cool & dry weather continues through Thursday with another chance for showers & thunderstorms looking likely Friday into Saturday. Additional chances for showers & thunderstorms look possible over the Memorial Day weekend, but it won't be a washout of a weekend. Temperatures return to more seasonable values Friday into saturday, & could warm into the 80s Sunday & Monday. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1244 AM CDT Mon May 18 2026 Thunderstorms impacts & gusty winds up to 30 kts will impact EAU over the next 1-2 hours, but otherwise only an hour or two of light showers are expected at MSP & RNH. Very messy ceilings forecast through sunrise, with guidance wanting to fill in low MVFR to IFR stratus across the area, but some drier air mixing in after the rain ends has temporarily scoured out low clouds across much of the area. I do expect these low clouds to fill back in into the early morning hours, but we could see a few hours of VFR until then. We'll stay dry into this afternoon with low stratus likely sticking around through the day. Ceilings will be borderline MVFR/IFR, with IFR favored during themorning & some slight improvement to MVFR possible during the afternoon. Another round of rain showers arrives this evening, with a few thunderstorms likely from southern Minnesota into western Wisconsin. KMSP...Could see sporadic wind gusts to 30 kts out of the east over the next hour or two as drier air behind the rain creates some turbulent winds. IFR ceilings look likely by sunrise & we'll likely hold on to these low ceilings into the afternoon. SOme improvement to above 1000 ft is likely during the afternoon, but ceilings could drop to IFR again tomorrow evening. Timing of the next round of rain looks to begin a as rain showers around 6-7 PM, with the best chance for some thunder between 9 PM to midnight. Scattered rain showers will continue on & off into early Tuesday morning. /OUTLOOK FOR KMSP/ TUE...MVFR cigs becoming VFR. Wind NW 10-15G25kts. WED...VFR. Wind lgt and vrb. THU...VFR. Wind SE 10G20kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...ETA AVIATION...ETA  082 FXUS65 KLKN 180822 AFDLKN Area Forecast Discussion National Weather Service Elko NV 122 AM PDT Mon May 18 2026 .KEY MESSAGES... * Temperatures will be cold with below normal readings at all locations today * Overnight lows are expected to drop to below freezing this morning * A slow warmup will start today and persist through the rest of the week && .UPDATE... Issued at 112 AM PDT Mon May 18 2026 Added patchy freezing fog to the valleys in northern Nevada due to the precipitation received over the area yesterday. Skies are expected to scatter out later this morning. The freezing fog is expected to burn off quickly due to the early sunrise. No other changes have been made. && .DISCUSSION... (This evening through next Saturday) WEATHER PATTERN OVERVIEW: Strong late season upper trough currently pushing into northern Nevada has over-performed so far with respect to prior forecasts across Humboldt and Elko counties as snowfall with the front has kept temperatures cooler than expected and with precipitation amounts higher than forecast. Elko so far had seen about 0.21” of water which fell as 1.6 inches of snow so far this morning. Winnemucca has seen 0.17” of water including 0.2” of snow so far. Models suggest that this performance should continue as the front moves into central Nevada this afternoon and evening. Still think the snow rain transition will be at 4500 feet, but could drop to valley floors if clouds can keep the sun at bay. Winds are still expected to be the main story with this system though as model trends outside of the NBM support current wind headlines across northern and central Nevada. The NBM is the low outlier with respect to winds so went ahead and upped the winds to better capture current trends with this system. This afternoon the precipitation will become more isolated to scattered, and become more convective in nature as the upper low moves overhead bringing stronger dynamical lift. So it would not be a surprise to see a few rumbles of thunder this afternoon especially across central NV as better instability develops. Overall amounts look to be better with up to an additional 0.10” of water for the valleys and 1” to 3” of snow for the mountains of northern NV. Amounts for central NV have risen too, with precipitation approaching Eureka and snow starting in Ely. Current trends favor 0.05” to 0.5” of water for the valleys, and up to 2” to 7” for the mountains, with the higher amounts favoring eastern White Pine County. Upper trough look to make its exit across Utah and into CO Monday afternoon. Temperatures this afternoon and Monday will be cool, with highs in the 30s and 40s today, recovering into the 40s and 50s Monday afternoon. After Monday weak WNW flow will develop across NV along with weak and subtle ridging aloft. This will be in place through next weekend allowing for quiet conditions to return, along with a warming trend that will see temperatures warm back into the upper 70 to low 80s by next Sunday. Overnight lows will bottom out Monday morning in the upper teens to upper 20s, however as the warming trend gets under way lows to will warm back above freezing, reaching the upper 30s to upper 40s by Sunday night. Winds after Monday will shift back to the west to northwest, with speeds of 10 MPH to 20 MPH with gust up to 30 MPH in the afternoons. FORECAST CONFIDENCE & DEVIATIONS: Departure: Went ahead and had to bump up the winds/wind gusts for the High Wind Warning and wind advisory areas across Humboldt, N Elko, S Lander, S Eureka, N Nye, and White Pine Counties as the NBM winds were not representative of current trends. There is high confidence for strong northerly winds Sunday through Monday morning as upper trough digs through easternNevada. There is high confidence for scattered to numerous light rain and snow showers for Elko and White Pine counties as upper trough pushes strong cold front through the region through Monday morning. There is high confidence for isolated to scattered light valley rain and mountain snow showers for western NV through Monday morning. There is high confidence for a return to quiet weather conditions through the following weekend as WNW flow aloft with subtle ridging allows temperatures to warm back into the upper 60s to low 80s by next Sunday. && .AVIATION... Patchy FZFG is possible this morning across the northern valley locations with VCFG near KEKO. Winds will be breezy in the afternoon NW10-20G30KT. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...86/98 AVIATION...98  171 FXUS64 KOUN 180824 AFDOUN Area Forecast Discussion National Weather Service Norman OK 324 AM CDT Mon May 18 2026 ...New NEAR TERM, SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 315 AM CDT Mon May 18 2026 - There is a risk for strong to severe thunderstorms from this afternoon through Tuesday. - Critical fire weather conditions are possible for far western Oklahoma into western north Texas this afternoon - Very warm temperatures are expected today with cooler weather by Tuesday. && .NEAR TERM... (Through Monday) Issued at 315 AM CDT Mon May 18 2026 A negatively-tilted trough will lift into the Central Plains this afternoon with a trailing dryline located along the 100th meridian. With the synoptic-scale forcing/ascent lifting to the northeast, thunderstorm development along the dryline remains uncertain as warm mid-level temperatures at the base of the elevated mixed layer (EML) will result in capping inversion at ~750 mb. In addition, low-level convergence along the dryline will be minimal/weak with the surface low and attendant backed winds to the northeast of Oklahoma. The highest chance for development along the dryline is across northwest Oklahoma, which is in closest proximity to the wave. Even so, the chance of development during the late afternoon/early evening is only around 20 to 30%. The chance of development decreases with southward extent along the dryline--but isn't zero. If thunderstorms develop, instability and vertical wind shear will be sufficient for supercells with CAPE between 3000-3500 J/kg and 0-6 km shear between 30 to 35 knots. By evening, the low- level jet will amplify with 50 to 60 knot winds. The strengthening low-level jet will increase low-level wind shear, resulting in enlarged, clockwise- curved hodographs that will be favorable for tornadoes--including strong tornadoes. As a result, if there are any ongoing supercells in the evening, they will have an increasing tornado potential. In addition to the dryline, another feature will be a subtle wave embedded in the subtropical jet stream (STJ) that will lift northward into south central/southeast Oklahoma. This wave may result in a few showers and thunderstorms today. While it appears likely this activity will be elevated and associated with isentropic/ascent warm air advection, there is a low chance this activity could become surface-based with a risk of strong to severe thunderstorms. To the west of the dryline, fire weather conditions will be a concern in the afternoon. Hot temperatures, gusty southerly winds, and low humidity will result in critical fire weather conditions. The worst fire weather conditions will be across the Oklahoma and Texas panhandles. However, far western Oklahoma and adjacent parts of western north Texas will be right on the edge. Depending on the exact location of the dryline, there will likely be a very tight relative humidity gradient near the 100th meridian (Oklahoma/Texas state line). Therefore, the Fire Weather Watch was upgraded to a Red Flag Warning except for Jackson County. It could very well be a situation where the fire weather conditions are worse in the western part of the counties compared to the eastern part of the counties. In addition to the risk of severe and fire weather, a tight surface pressure gradient will result in breezy southerly winds today. Mahale && .SHORT TERM... (Monday night through Wednesday night) Issued at 315 AM CDT Mon May 18 2026 A cold front will enter northern Oklahoma late this evening, which will likely result in a line of thunderstorms developing along the front. The line of thunderstorms will move to the southeast Monday night into Tuesday morning with the cold front with a threat for strong to severe thunderstorms. Damaging windgusts and embedded, QLCS tornadoes would be the potential hazards. However, the tendency for the cold front to undercut the line of thunderstorms and unfavorable shear vectors/line orientation should reduce the QLCS tornado risk. Cooler weather and northerly winds are expected in the front's wake Tuesday afternoon. Another wave is forecast to approach late Tuesday night into Wednesday, which will result in increasing isentropic ascent/warm air advection to the north of the cold front. Widespread elevated showers and thunderstorms are possible with the potential hazards being heavy rainfall/flooding and hail. The location with the highest chance for heavy rainfall is south central/southeast Oklahoma. Mahale && .LONG TERM... (Thursday through Sunday) Issued at 315 AM CDT Mon May 18 2026 An active subtropical jet stream (STJ) with subtle waves lifting into the Southern Plains will result in a daily chance of showers/storms through the end the week into next weekend. At this time, there is no day that has an appreciable risk for severe weather. Temperatures are expected to be seasonable for late May. Mahale && .AVIATION... (06Z TAFS) Issued at 1026 PM CDT Sun May 17 2026 VFR/MVFR ceilings expected this TAF period. Breezy southerly winds will continue overnight into Monday with wind speeds increasing Monday morning. A cold front is expected to be approaching NW OK late Monday evening. There is a chance that a few storms develop near the dryline to the west Monday afternoon/evening. If these storms develop, they could move into parts of western OK but the higher chance for storms is expected to start Monday night as the cold front moves across the area. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 86 61 71 55 / 10 80 40 80 Hobart OK 93 60 75 54 / 10 60 30 60 Wichita Falls TX 92 68 82 58 / 20 50 70 70 Gage OK 96 49 73 46 / 10 20 0 10 Ponca City OK 89 58 70 53 / 10 80 30 30 Durant OK 88 74 84 64 / 30 20 90 70 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Wind Advisory until 10 PM CDT this evening for OKZ004>027- 034>038. Red Flag Warning from 1 PM this afternoon to 9 PM CDT this evening for OKZ004-009-014-021-033-034. TX...Red Flag Warning from 1 PM this afternoon to 9 PM CDT this evening for TXZ083-084. && $$ NEAR TERM...10 SHORT TERM...10 LONG TERM....10 AVIATION...25  270 FXUS63 KDVN 180827 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 327 AM CDT Mon May 18 2026 .KEY MESSAGES... - Another round of storms tonight, with the chance for some of them to be strong to severe. - Turning cooler and breezy Tuesday behind a cold front, with dry conditions expected to then last through at least Thursday. && .SHORT TERM /THROUGH TONIGHT/... Issued at 315 AM CDT Mon May 18 2026 Will walk out ongoing linear MCS that has become mainly outflow dominant, although a few isolated strong wind gusts may still occur. Also some isolated precursor WAA cells have developed ahead of the main line and with an elevated nature may produce some hail. Such a weakening larger system and inherent pressure perturbations may produce more trouble with wake low winds gushing out of the system's backside, possibly of 45 to 55+ MPH. Some of the CAMs even suggested this by mid morning south of I-80 acrs west central IL and far southeast IA. Areas of post-convective line stratiform rain with embedded thunder to be the last to clear as the morning progresses. Then again it's the same scenario of how much the convective debris can clear to allow for some heating, and also aided by breezy south to southwest sfc winds again this afternoon. Will go with 50 percentile widespread low 80s for highs today with sfc DPTs remaining in the 60s. The local area should remain dry while the current system lights up renewed convection to the south acrs central MO into central IL. Tonight...may be a similar scenario as to what has and is occurring this Sunday night/Monday morning. The main upper trof will dig out acrs the east central plains with mid and upper jet support, and the main sfc front located along the MO RVR Valley. MCS generation tools all come together to suggest rapid and strong convection to fire late this afternoon from central KS and up the MO RVR Valley. Storm propagation vectors and CAPE "hunger" has this activity growing upscale and feeding east with aid of 40-50 KT SSW LLJ flow as another squall line moves east acrs IA and northern MO. There may be more support and a probable earlier start to allow some of this activity to still be strong to severe with damaging straight line winds(as opposed to this Monday AM) as the linear MCS arrives. 0-3KM shear vectors and LLVL THTA-E lapse rates may also support some meso- vortice type spin up tornadoes along any LEWP or comma head updraft- downdraft balance regions. Locally heavy rain with the passing storm lines with high rates, but again progressive nature of the system should preclude much of a widespread flash flood threat. Would expect a weakening trend with the convection as it propagates eastward acrs the rest of the DVN CWA into the late night hours and into early Tuesday morning as storm outflow outraces the main line again. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 315 AM CDT Mon May 18 2026 Tuesday...Morning convective debris and possibly a few post-frontal isolated light showers to eventually clear off for a blustery and cooler day. A large temp range acrs the CWA from west-to-east, with the east experiencing 12 hour high temps in the morning along and just post-frontal and then falling off into the 60s. The rest of the week looks below normal under high pressure until moderation occurs into the start of the weekend. Also mainly dry until an upstream upper trof tries to battle it's way eastward into the ridge complex with some moisture draw for increasing precip chances by Friday. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1250 AM CDT Mon May 18 2026 Will walk the line of weakening showers and thunderstorms through the TAF sites through 11z this morning. They may have an hour of higher wind gusts of 35-45 KTs or so, then transition to more of stratiform rain bands with embedded thunder behind the main line. This secondary activity to wane by 15z Monday morning. Away from the storms breezy southerly sfc winds gusting up to at least 25 KTs, and aloft strong LLVL jet of 45-55 KTs. Later Monday afternoon again gusty southerly winds and mainly VFR clouds lingering into Monday evening, then the watch will be on for another line of thunderstorms moving in from the west toward and after the end of the TAF period. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...12 LONG TERM...12 AVIATION...12  628 FXUS63 KARX 180833 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 333 AM CDT Mon May 18 2026 .KEY MESSAGES... - Severe storm threat returns through the area today with primary concern for damaging winds and secondary concerns of large hail and isolated tornadoes. Higher confidence for severe storms and storm initiation lies southwest of the forecast area into central and southwest Iowa with storms weakening as they lift northeast through the evening hours. - Colder with showers for Tuesday with colder temperatures sticking around into the weekend. Low chance for some local areas to see Frost Tuesday and Wednesday nights. && .DISCUSSION... Issued at 316 AM CDT Mon May 18 2026 Morning Observations & Synoptic Setup Today: An upper level longwave trough over the Rocky Mountain West on GOES water vapor imagery loops, evidently amplifying in enhancement of meridional GOES-derived upper level jet streaks lee of the Rocky Mountains, causes cyclogenesis over the Central Plains and subsequent reinvigoration of low level moisture transport, resulting in a similar severe weather set up as Sunday for the Upper Mississippi River Valley through this evening into tonight. Low Level Capping Limiting Local, Widespread Confidence Today: While it remains quite moist in the low levels early this morning, GOES upper level water vapor imagery loops and derived upper level winds depict a meagerly zonal perturbation eradicating moisture from the local forecast area to the east, tied to the long bowing non-severe radar returns from southern Iowa through northern Wisconsin. High resolution model analyses (18.06/18.00Z) suggest 850mb/925mb drying persisting through the early afternoon before cyclogenesis along the lingering low level baroclinic boundary spanning from the Mid Missouri River Valley to the northeast, kinked by anticyclonic rotation over Minnesota, initiates low level moisture transport northeastward towards the forecast area. The local drier, warmer low level air will cause another capping inversion, inherently increasing dependence on northern extent of moisture return (i.e., warm front) through the forecast area today. Current, further limiting factors include diurnal timing close to sunset and deamplification of the upper level wave as it nears the Upper Mississippi River Valley through the afternoon, both decreasing confidence in northerly frontal transport. Summarily, the current temporal and resultant spatial window for convection to become surface based or even achieve sufficient forcing to access enhanced MUCAPE (2000+ J/kg) from steeper mid level lapse rates limits local confidence. Furthermore, high resolution soundings and spatial analysis of available shear magnitudes are messy, at best. Splotches of severe storm supportive shear values across the forecast area remain tied closer to the actual frontal boundary, from southwest to northeast Minnesota through the afternoon and evening, eventually coinciding into the nighttime hours when a local capping inversion is more likely. The two synoptic factors or scenarios that would increase local severe threat through today would be a stronger wave lifting north out of the Southern Plains this morning or limited eradication of low level moisture this morning. Severe Storm Potential Timing, Location, & Impacts Today: Current confidence for damaging winds as the main hazard primarily along southwestern peripheral counties in northeast Iowa potentially into bordering counties of southwest Wisconsin and southeast Minnesota with secondary hazards of large hail and isolated tornado(es) this evening into tonight. While all hinge on northern extent of return flow and warm front location, damaging wind concerns are more widespread into western and central Wisconsin given the rapid ejection of the trough causing quick storm motions of potentially 50+ kts. Colder with Patchy Showers Tuesday: Eventually the upper level trough axis traverses east through the forecast overnight into Tuesday morning, advecting light rain showers into early Tuesday morning with additional cumulus popcorn shower potential into the daytime from steepening low level lapse rates within a low level CAA regime. Quite chilly showers to boot with daytime highs in the mid 50s to 60s and confidence for 925mb/850mb temperatures dropping 15+ C from 19.00Z to 20.00Z. Colder & Mostly Dry Into The Weekend: The colder than normal temperatures expected to stick around the Upper Mississippi River Valley until the weekend due to lingering low level anticyclonic flow locking in advection from a Canadian Continental quasi-polar airmass situated over the northern Great Lakes. Current confidence in lowest temperatures Tuesday night may graze Frost headlines along western peripheral counties in southeast Minnesota as well as northern peripheral counties in central Wisconsin Tuesday and WEdnesday nights. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1242 AM CDT Mon May 18 2026 Line of decaying storms seen shifting east through local forecast area, over Mississippi River Valley at 18.06Z TAF issuance. Strong winds along and behind this line will be main impact besides scattered embedded thunder. Strong winds persist behind this line for the next couple of hours. MVFR-IFR ceilings with MVFR visibilities possible with ongoing early morning rain. VFR expected through the late morning into the early afternoon before thunder chances increase from southwest to northeast again Monday evening and night. Storms quickly progress from southwest to northeast with damaging winds as main severe hazard. Storms exit the area with frontal passage overnight into Tuesday morning. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...JAR AVIATION...JAR  920 FXUS62 KKEY 180840 AFDKEY Area Forecast Discussion National Weather Service Key West FL 440 AM EDT Mon May 18 2026 ...New DISCUSSION, MARINE, AVIATION... .KEY MESSAGES... - Very warm and humid conditions expected across the Florida Keys this week, and will lead to a moderate to high risk for heat related illnesses. - Rain and thunder chances have peaked, and will gradually decrease through the middle of the week. - A period of on and off breezy conditions expected through tonight, and will help to mitigate some of the discomfort from warm overnight temperatures. && .DISCUSSION... Issued at 440 AM EDT Mon May 18 2026 A pocket of relatively drier air moved in during the afternoon and evening on Sunday, and did not recover as well as we had hoped. Therefore, the coverage of showers has been underperforming, at least as the island chain is concerned. It remained quite active across the surrounding coastal waters, but unfortunately, very few of these showers passed over the Keys. Temperatures this hour remain in the lower 80s with dew points in the mid 70s. Thankfully, breezy conditions developed and have aided in at least taking the edge off the muggy conditions. For today, additional moisture to our east should pivot in throughout the day today. This combined with an already accelerated flow, should help to smash any mesoscale boundaries out there, allowing for showers to increase in coverage again. This enhanced moisture pool will linger through tonight and gradually begin scouring out starting Tuesday. This will not be a fast process and rain chances will be slow to diminish through the week. Meanwhile, a high pressure near Bermuda will flatten over the next several days, weakening the pressure gradient through the end of the week. This will lead to generally a slackening of winds, though there will still be some peaks in the evenings at times. By the end of the week we may have an easterly undulation move through the Bahamas and along the east coast of Florida, injecting more moisture back across the area, and subsequently rain chances. It's too far out to get our hopes up at this time. && .MARINE... Issued at 440 AM EDT Mon May 18 2026 Moderate to fresh breezes prevail this morning and will continue through the overnight. Small Craft Exercise Caution headlines are in effect for all of the Florida Keys coastal waters. A high pressure near Bermuda will flatten starting Tuesday and the pressure gradient across the Keys will gradually lessen. This will lead to a gradual, but generally slackening of breezes through the week. We can still expect some nocturnal peaks at times, before breezes return to light to gentle by Thursday. Thereafter, breezes may freshen slightly as an easterly undulation moves across the Bahamas. && .AVIATION... (06Z TAFS) Issued at 440 AM EDT Mon May 18 2026 VFR conditions are expected outside of any passing shower. East to southeast winds will remain breezy at times through the forecast period. Not expecting showers necessarily all day, however, confidence on when breaks will occur and for how long is very uncertain. && .PRELIMINARY POINT TEMPS/POPS... Key West 91 80 91 80 / 40 40 40 30 Marathon 87 79 86 80 / 40 40 40 30 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...LIW Aviation/Nowcasts....LIW Data Acquisition.....DDR/LIW Visit us on the web at weather.gov/key Follow us on Facebook and Twitter at: www.facebook.com/nwskeywest www.twitter.com/nwskeywest  913 FXUS64 KJAN 180839 AFDJAN Area Forecast Discussion National Weather Service Jackson MS 339 AM CDT Mon May 18 2026 ...New DISCUSSION... .KEY MESSAGES... - Heat and humidity more typical of early summer can be expected along with increasing thunderstorm chances this week. - Isolated severe storms are possible in the northwest Tuesday. && .DISCUSSION... Issued at 330 AM CDT Mon May 18 2026 Through Tonight: Continued warmer than normal through the period with afternoon rain chances limited to the southern half of the CWA. Surface ridging from the east will remain across the Gulf coast states while our flow aloft remains southwesterly downstream of an upper level trough swinging across the Four Corners region. This will help maintain a warm moist airmass over our CWA. Latest PWATs were running just above an inch and three quarters with surface dew points being observed in the upper 60s to lower 70s. Wl start off with some patchy fog in the southeast but daytime heating of our moist airmass will lead to isolated to scattered showers and thunderstorms during the afternoon and mainly south of Interstate 20. The distinct diurnal nature of the convection will result in the convection dying off rapidly around sunset. The probabilities of fog development are lower for Tuesday morning but patchy light early morning fog is possible in the southeast again. /22/ Tuesday through Sunday: A frontal boundary will continue to progress towards the southeast before stalling north of the CWA. Ongoing showers and storm chances are expected through the extended period. Highs (ranging in the 80s) will remain near seasonal averages and lows (upper 60s/near 70 degrees) will run +5-8 degrees above seasonal averages over the extended as well. Precip chances ranging from 40% to 95% with greatest chances on Wednesday (95%) and Friday (90%) with 80-95% are likely. On Tuesday, the boundary gradually push into the area, interaction with the present deep-layer shear and CAPE near the MS Delta, may promote a few severe storms in the area. As a result, a 'Marginal' risk for severe weather will be possible over the MS Delta region Tuesday. A HWO graphic will be introduced to reflect the severe risk area. As the boundary stalls, multiple shortwave disturbances are expected to traverse the region, providing addition moisture and increasing rain chances Wednesday into the weekend. Organized severe weather is not anticipated as instability won't be as favorable, however, an isolated severe storm or two may be possible. Estimate rainfall amounts may range from 1.0-3.5 inches over the course of this week and the weekend. Received rainfall will help alleviate the ongoing drought over the ArkLaMiss region. /SW/ && .AVIATION... (06Z TAFS) Issued at 102 AM CDT Mon May 18 2026 MVFR cigs were already being observed at HEZ at 0530Z. MVFR/IFR cigs wl develop cntrl and south by 10Z while the northern TAF sites remain in VFR. Conditions wl improve by 15Z and a gusty se-s wind 18-20kts wl develop areawide by 16Z. These gusts will subside by 23Z. There is a low chance of isolated SHRA/TSRA in vcty of HEZ after 19Z and until 23Z. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 87 72 88 70 / 10 10 40 50 Meridian 88 70 89 68 / 10 0 20 30 Vicksburg 89 73 89 70 / 10 10 40 60 Hattiesburg 88 71 88 69 / 30 0 20 0 Natchez 89 73 89 71 / 30 20 50 60 Greenville 90 74 90 70 / 10 10 40 60 Greenwood 89 73 90 70 / 10 10 30 70 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ 22/SW/22  948 FXUS64 KMAF 180841 AFDMAF Area Forecast Discussion National Weather Service Midland/Odessa TX 341 AM CDT Mon May 18 2026 ...New SHORT TERM, LONG TERM, FIRE WEATHER... .KEY MESSAGES... Updated at 333 AM CDT Mon May 18 2026 - Summer-like heat expected through Tuesday. Highs along portions of the Rio Grande may reach between 105 and 110 degrees during this time frame. - Critical fire weather conditions expected for the Guadalupe Mountains, southeast New Mexico, and the northwest Permian Basin this afternoon and evening. - Rain and storm chances increase (40-80% chances) by the middle to latter part of the week. We will be monitoring a few strong to severe storms each day. Heavy rainfall may lead to flooding concerns over locations east of the Pecos River Wednesday into Thursday. && .SHORT TERM... (Today through Tuesday afternoon) Issued at 333 AM CDT Mon May 18 2026 Another hot and windy day is expected across the region, particularly over southeast New Mexico and adjacent portions of West Texas. Antecedent dry conditions combined with the dry air will make for critical fire weather conditions. More information on that can be found below in the fire weather discussion. Many locations will reach into the mid to upper 90s with a number of spots near the century mark. Winds will decay by tonight, but temperatures will only fall into the 60s and 70s. A cold front approaches the region by Tuesday morning and slowly stalls near the Pecos River Valley. The front and present dryline combine to increase storm chances across the eastern portions of the CWA. A few strong to severe storms will be possible Tuesday afternoon and evening. Depending on the timing and strength of the front, temperatures will be a touch cooler for most compared to today, though will still reach into the low to mid 90s. Highs in the 100s will be seen along the Rio Grande. -Stickney && .LONG TERM... (Tuesday night through Sunday) Issued at 333 AM CDT Mon May 18 2026 Tuesday night and into Wednesday sees an upper level disturbance move across from the west. This combined with the dryline moved further west will lead to higher rain chances across most of the region for Wednesday and into Thursday. Strong to severe storms will be possible on both days, but it remains to be seen what hazards these storms will contain and just how much rain will fall and where. Below normal temperatures will take hold from Wednesday through at least Saturday as easterly flow and a favorable upper level environment keep temperatures on the cool side for mid to late May. Low (10-20%) rain chances hold on from Friday and into the weekend particularly across the Davis Mountains and eastern portions of the CWA. -Stickney && .AVIATION... (06Z TAFS) Issued at 1134 PM CDT Sun May 17 2026 VFR conditions will continue the next 24 hours at the TAF sites though MVFR CIGs could approach MAF to the east near 12Z. Gusty winds will subside for a few hours from 09-15Z before increasing again due to daytime heating. Hennig && .FIRE WEATHER... Issued at 333 AM CDT Mon May 18 2026 Have expanded the inherited Red Flag Warning to include most of Culberson County as well as Andrews County. Well above normal temperatures, exceedingly dry conditions (both a lack of rainfall and critically low min RHs), and breezy winds will make for critical fire weather conditions across southeast New Mexico and adjacent portions of West Texas this afternoon. An upper level low moving into the Rockies will provide the increasing southwesterly winds that not only aide in fire spread, but can also be attributed to the expected above normal temperatures today. Beyond today, critically low relative humidities return on Tuesday, but winds will be much lighter. Thenearby dryline sharpens on Wednesday and is forced back towards the western edge of the CWA bringing strong moisture return and a chance for wetting rains for Wednesday and Thursday. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 99 71 90 61 / 0 10 30 40 Carlsbad 94 63 94 61 / 0 0 0 10 Dryden 102 73 97 68 / 0 0 30 20 Fort Stockton 100 67 98 64 / 0 0 10 20 Guadalupe Pass 84 61 85 61 / 0 0 0 0 Hobbs 93 59 91 57 / 0 0 0 10 Marfa 91 54 92 53 / 0 0 0 0 Midland Intl Airport 97 69 93 62 / 0 0 10 30 Odessa 97 69 93 63 / 0 0 10 30 Wink 98 63 96 63 / 0 0 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...Red Flag Warning from noon CDT /11 AM MDT/ today to 9 PM CDT /8 PM MDT/ this evening for Andrews-Dawson-Eastern Culberson- Gaines-Guadalupe Mountains Above 7000 Feet-Guadalupe and Delaware Mountains-Loving-Van Horn and Highway 54 Corridor- Winkler. NM...Red Flag Warning from 11 AM this morning to 8 PM MDT this evening for Chaves Plains-Eddy Plains-Lea-Sacramento Foothills and Guadalupe Mountains. && $$ SHORT TERM...93 LONG TERM....93 AVIATION...10  017 FXUS63 KILX 180843 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 343 AM CDT Mon May 18 2026 .KEY MESSAGES... - There is a Slight Risk (level 2 of 5) for severe weather areawide today. While all severe weather hazards will be possible, damaging wind gusts in excess of 60 mph will be the most likely. - Additional thunderstorms will develop along an advancing cold front on Tuesday, with a Slight Risk (level 2 of 5) for severe weather in areas east of Interstate 55. Once again, damaging wind gusts in excess of 60 mph will be the most likely hazard. && .DISCUSSION... Issued at 318 AM CDT Mon May 18 2026 ...Active Convective Complex This Morning... Radar analysis early this morning reveals a robust linear Mesoscale Convective System (MCS) stretching from north-central Wisconsin down through southeast Iowa, central Missouri, and into eastern Kansas. Strong, consolidating cold pools have allowed a leading outflow boundary to outrun the primary convective line. Convective-allowing models (CAMs) exhibit high confidence that this system will maintain its structural integrity as it pushes eastward into the central Illinois forecast area later this morning. Sustaining this morning activity is a potent 40-50 kt low-level jet (LLJ) parked directly over central Illinois. This feature, working in tandem with subtle mid-level shortwaves embedded within the southwest flow aloft, is providing ample synoptic lift and elevated instability (MUCAPE around 1500 J/kg). While weak deep- layer shear > 30 kts) should keep the morning activity largely disorganized and sub-severe, mid-level dry air and localized evaporative cooling could help overcome the waning morning inversion, supporting isolated severe hail or localized downburst winds. As an interesting aside, numerous runs of the HRRR overnight depicted an area of 40-50 kt surface winds within the trailing stratiform region, in an otherwise unassuming area. While it is uncertain if the model is resolving a wake-low or meso-high feature, the trend bears close observation. If these winds materialize, a short- fused wind advisory or high wind warning may become necessary for a brief window this afternoon. .Severe Potential This Afternoon... By early afternoon, attention shifts to areas near and east of a Taylorville-to- Champaign line. A compact shortwave trough is progged to lift northeastward out of southeast Missouri around 18z, enhancing background kinematic shear and dynamic forcing across a highly buoyant boundary layer. In this zone, temperatures climbing toward the 80-degree mark and dewpoints hovering near 70 degrees will yield SBCAPE values exceeding 2000 J/kg. While the incoming shortwave will likely spark an increase in convective coverage ahead of the main morning line, individual storm intensity remains somewhat conditional. An important limiting factor is that mid-level lapse rates will likely deteriorate through the afternoon as the residual Elevated Mixed Layer (EML) exits to the east. However, as deep- layer shear ticks upward across southeast Illinois later today, localized enhancements within the main convective line remain a possibility. This could yield bowing segments capable of producing the full spectrum of severe weather hazards as the line advances into the southeastern counties. As an interesting aside, numerous runs of the HRRR overnight depicted an area of 40-50 kt surface winds within the trailing stratiform region, in an otherwise unassuming area. While it is uncertain if the model is resolving a wake-low or meso-high feature, the trend bears close observation. If these winds materialize, a short- fused wind advisory or high wind warning may become necessary for a brief window this afternoon. The severe threat will not completely diminish after dark. Additional shortwaves interacting with the persistent 40-50 kt LLJ core will likely sustain elevated convective development ahead of the approaching cold front well into Tuesday morning. ...Conditional Severe Threat and Linear Transition on Tuesday... Significant forecasting uncertainty shrouds the Tuesday period, primarily driven by nebulous synoptic forcing and the likelihood of extensive morning convective debris. If widespread cloud cover and rain persist deep into the morning hours, afternoon destabilization will be severely limited, rendering the severe weather threat highly conditional. At this juncture, the highest probability for boundary layer recovery exists near and south of the Interstate 72 corridor, extending through southeast Illinois ahead of the advancing cold front. Should adequate destabilization manifest, favorable instability and deep-layer shear profiles would initially support discrete supercellular structures. However, because the regional shear vectors are oriented nearly parallel to the surface frontal boundary, any discrete activity is expected to transition rapidly into a linear MCS as the front sweeps through Tuesday evening. ...Hydrological Concerns and High QPF Variability... Confidence remains exceptionally high that multiple rounds of convective rainfall will impact the entire region through Tuesday evening. However, the complex, training nature of this pattern introduces severe spatial discrepancies in expected precipitation totals. 48-hour HREF Localized Probability Match Mean (LPMM) QPF projections valid through 00z Wednesday demonstrate a stark variance, showing localized pockets picking up a mere quarter-inch while training cores could easily exceed 4.5 inches. Current model guidance continues to pinpoint the highest risk for these excessive, flood-producing rainfall totals along and south of the I-72 corridor, where repeated convective elements are most likely to anchor. ...Midweek Clearing Followed by a Wet Weekend Outlook... Wednesday through Thursday: A welcome pattern shift occurs mid- week as a cooler, significantly more stable post-frontal regime takes hold. Continental high pressure building into the Midwest will clear skies and lower humidity levels, offering a brief reprieve from the active weather. Friday through Sunday: The dry spell will be short-lived. Global deterministic models are in notably better agreement, signaling a return to a wetter, unsettled pattern by late week. As the surface high pressure slants eastward, a potent mid-level shortwave will advance across the central U.S. A steady plume of Gulf moisture combined with a series of minor shortwave impulses lifting northeast from the Southern Plains will keep central Illinois susceptible to multiple rounds of scattered showers. While weak kinematic profiles should heavily restrict the overall severe weather risk, a gradual build-up of instability over the weekend will support widespread thunderstorm development. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1231 AM CDT Mon May 18 2026 Low level wind shear is expected through early morning across central IL as strong SSW winds aloft around 50 kts continue. A line of thunderstorms will continue approaching from the west overnight, anticipated to arrive at KPIA by 12Z, KSPI and KBMI by 14Z, and KDEC/KCMI by 15Z. Have included a 3-hour tempo group for MVFR cigs/vsbys for these thunderstorms, then scattered showers are likely to continue for a few to several hours after the storms, although with generally VFR conditions. Anticipate briefly worse conditions in any of the stronger storms. Winds S 12-20 kts overnight with a few higher gusts. Winds increase to 15-20 kts with gusts 25-30 kts after 12Z.&& .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$ KEY MESSAGES...MJA DISCUSSION...MJA AVIATION...37  251 FXUS61 KALY 180846 AFDALY Area Forecast Discussion National Weather Service Albany NY 446 AM EDT Mon May 18 2026 .WHAT HAS CHANGED... Marginal Risk (Level 1 of 5) for severe thunderstorms for Herkimer and Hamilton Counties today and tonight. Marginal (Level 1 of 5) to Slight Risk (Level 2 of 5) for severe thunderstorms Tue across most of eastern NY and western New England with damaging winds the main threat. Marginal Risk (Level 1 of 5) for isolated severe threat south and east of the Capital District on Wed. Winds/wind gusts slightly increased for Tue through Wed with frontal passage mid week, as cooler temps return late Wed-Thu. && .KEY MESSAGES... 1) Well above-normal temps continue into the mid-week. The NWS HeatRisk is in the moderate category for heat-related impacts, especially on Tue. 2) Coverage of showers and t-storms increases Tue pm into Wed ahead of a cold front. Some strong to potentially severe t-storms possible Tue pm/early evening and also Wed south of the Capital District. 3) A return to more seasonable temps is expected late this week with the next chance for widespread rain being next weekend. && .DISCUSSION... KEY MESSAGE 1... A mid and upper level ridge near the East Coast will bring above normal temps to the forecast area today-Tue. The ridge builds in this morning, as a weak frontal boundary lifts north, as a warm front with some isolated to widely scattered showers and t-storms over the southern Adirondacks and Lake George Region. Low and mid level heights increase 1-2+ STDEVs above normal based on the latest NAEFS. H850 temps will rise 2-3 STDEVS above normal by Tue with the actual temps in the +15C to +19C range. Max temps today will be in the upper 80s to lower 90s in the valleys and upper 70s to mid 80s over the higher terrain. Heat indices/apparent temps will be in the 80s to lower 90s. An isolated pop-up shower/t-storm can not be ruled out, especially late in the pm/early evening over the west/southwest Adirondacks. Isolated strong to damaging wind gusts are possible based on the SPC Day 1 Marginal Risk. Lows will be quite mild tonight in the 60s with some upper 50s over the higher terrain. The warmest day will be on Tue with max temps about 20 degrees above normal. The NBM continues to run warm and our forecast highs for Tue involves blending with persistence/prev fx and trimming by a few degrees based on H850 temps +16C to +19C with dewpts in the upper 50s to lower 60s (spotty mid 60s) was considered with the south/southwest boundary layer flow. Max temps will be more widespread in the lower 90s in the valleys and 80s over the hills and mtns. Some records could be tied or broken on Tue (see the Climate section below). A few isolated spots in the mid Hudson Valley may hit apparent temps/heat indices (feels-like temps) in the mid-90s, but the air temps will be close to the apparent temps. No heat advisories are planned at this time. However, the hot conditions with some moderate humidity levels have cause the NWS HeatRisk to be in the moderate category for most of the forecast area on Tue (spotty in the major category in the mid Hudson Valley). This category affects the population that are sensitive to heat, especially those without cooling systems/hydration, and some health systems and industries. The heat subsides by Wed with a cold frontal passage with some showers and t-storms. KEY MESSAGE 2... The coverage and intensity of convection is still uncertain Tue-Wed across eastern NY and western New England. SPC continues a Marginal (Level 1 of 5) to Slight Risk (Level 2 of 5) for severe weather across the forecast area Tue-Tue night. Some of the CAMs indicate a pre-frontal sfc trough/lake breeze boundary may focus convection in the afternoon (mid to late pm) and it extends into the early evening. The 0-6 km shear does not look exceptionally strong at 25-35 KT, but MLCAPEs may reach 1000-1500 J/kg especially along or north and west of Albany. The Slight Risk covers the western Mohawk Valley, southern Adirondacks and the Lake George Region. Steep low-level lapse rates will be in place with DCAPEs around 1000 J/kg. The latest ARW-WRF 1 & 2 support more coverage than the 3-km NAM or HRRR. The atmosphere becomes less capped with the front approaching Tue night. It becomes breezier ahead of the front. The main threat with any severe thunderstorms will be damaging winds. The instability wanes Tue night with the frontal boundary placement tricky for Wed. The latest forecast supports the front near the Capital District, southern VT and the northern Catskills in the late morning early pm and moving south quickly. The latest NBM probabilities for >1000 J/kg of SBCAPE Wed early pm are surpressed south and east of the Tri Cities towards the mid Hudson Valley and I-84 corridor. A few t-storms could be on the strong side closer to this area. SPC Day 3 Outlook has a Marginal Risk (Level 1 of 5) for locations south and east of the Capital District Wed pm for damaging wind gusts. It will become breezy in the wake of the front with west to northwest winds 10-20 mph with some gusts 25-35 mph. Max temps may range from the 60s to lower 70s over the western Mohawk/southern Dacks to the upper 80s to lower 90s over the mid Hudson Valley and NW CT. The Capital Region was favored in the upper 70s to lower 80s. Much cooler air filters in Wed night. KEY MESSAGE 3... Strong cold advection continues across the region Wed night with lows in the 40s to lower 50s with some upper 30s in the Adirondack Park, as the growing season begins there May 21st. A 1030 hPa sfc anticyclone builds in from southern Ontario and the Great Lakes Region on Thu. Temps will be near or slightly below normal in the 50s to lower 60s over the higher terrain and mid and upper 60s in the valleys. The cooler and drier weather continues Thu night thru Fri with some patchy to areas of frost possible in the southern Adirondacks. Wetter and more unsettled weather returns potentially Fri night into the Memorial Day Holiday weekend, as a warm front and a low pressure system may bring occasional showers with slightly cooler than normal temps. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... Through 06Z Tuesday, mainly VFR conditions are expected through the TAF period. However, upper level disturbances could bring a few showers/thunderstorms to KGFL between 10Z-14Z/Mon, and again 00Z-03Z/Tue. Brief MVFR/IFR Vsbys could occur within any heavier downpours. Light/variable winds will become southeast to south and increase to 8-12 KT by late morning, with some gusts of 15-20 KT possible this afternoon. South winds will persist after sunset at 5-10 KT. Outlook... Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: High Operational Impact. Breezy. Likely SHRA...TSRA. Wednesday Night: Low Operational Impact. Breezy. NO SIG WX. Thursday: Low Operational Impact. Breezy. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. NO SIG WX. && .CLIMATE... High Temperature Records: May 19 - Tuesday Albany, NY: 91 degrees set in 1989 Glens Falls, NY: 88 degrees set in 1989 Poughkeepsie, NY: 96 degrees set in 1962 && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ DISCUSSION...15 AVIATION...24 CLIMATE...31  312 FXUS63 KLOT 180847 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 347 AM CDT Mon May 18 2026 .KEY MESSAGES... - A few additional rounds of showers and thunderstorms today and Tuesday, some of which could be strong to severe mainly during the afternoon hours. - Summer-like warmth and breezy winds at times will prevail through Tuesday, then cooler temperatures return for the middle of the week. - Milder weather returns heading into the weekend, though with at least intermittent shower/thunderstorm potential. && .DISCUSSION... Issued at 347 AM CDT Mon May 18 2026 Regional radar mosaic shows a linear MCS moving across the Mississippi River into western WI/IL early this morning. There has been a notable weakening trend to the convection over the past few hours as the complex propagates into a region of decreasing deep- layer shear and low-level instability, though storms should continue to spread eastward this morning along a composite outflow boundary at the leading edge of the convection. In fact, recent radar trends indicate a few new cells developing ahead of the line near the Quad Cities, perhaps aided by enhanced ascent associated with one or more an apparent MCVs near the IA/IL/MO border. Gusty winds of 30-40 mph with the outflow and some small hail are possible with these storms early this morning, though the overall threat of organized severe weather appears low for the next several hours. Later this morning however, diurnal warming and associated destabilization along the east/southeast periphery of the complex remnants and outflow boundary may support renewed development/strengthening of convection with more of a severe threat into this afternoon. Though depending on how far the outflow boundary makes it this morning, this would likely be across the south/far east portions of the forecast area. Farther north/northwest, lingering stratiform rain and cloud cover this morning looks to limit destabilization and recent CAM trends have been consistently dry there during the day/evening. Farther to the west, early morning GOES vapor imagery indicates another mid-level short wave rounding the base of a western CONUS long-wave trough. Widespread strong convection is progged to develop late this afternoon and evening across KS/NE/IA once again in response, eventually growing upscale into another eastward- propagating linear MCS. Similarly to this morning, CAM runs continue to depict a similar weakening of this system as it reaches the Mississippi River and spreads into WI/IL early Tuesday morning with associated relatively low severe potential. The lingering MCS cold pool footprint and residual cloudiness will likely delay destabilization into midday Tuesday, though additional storm development appears possible across the southeast half of the forecast area Tuesday afternoon/evening as the cold front finally pushes through the forecast area. Stronger mid-level flow on the southeastern periphery of the aforementioned short wave will likely support enough storm organization for a hail/wind threat during this time. Following the cold front, surface high pressure is progged to build east into the western Great Lakes region Wednesday and Thursday. Dry, but breezy and cooler weather is expected both days, with temps mainly in the 60s, but only in the 50s near Lake Michigan with northeast-east flow off the lake. Nighttime lows in the 40s are expected. The high then drifts off to the east Thursday night, with the upper level pattern favoring a series of mid-level disturbances tracking through the area Friday into the weekend. This will support milder temperatures, but also some occasional shower/thunderstorm chances into the holiday weekend. Ratzer && .AVIATION /06Z TAFS THROUGH 12Z TUESDAY/... Issued at 100 AM CDT Mon May 18 2026 Forecast concerns for the terminals... - Line of showers and embedded thunderstorms to move through northern IL and northwest IN late tonight into Monday morning. A few storms could be strong with a threat for locally gusty winds. - Breezy south-southwest winds Monday afternoon with gusts around 25 kts. - Another period of showers and possible storms late Monday night into Tuesday morning. Latest radar imagery continues to show a line of showers and thunderstorms stretching from MN to KS that is racing towards northern IL and eventually northwest IN. Arrival time of this line continue to be around 09z at RFD and between 10-12z for the Chicago area terminals. While lightning trends within the line segment heading towards the terminals has been decreasing, recent AMDAR sounding out of MDW continue to show steep mid- level lapse rates (around 7-8 C/km) which could still support an occasional lightning strike as the line moves through. Additionally, a few stronger showers/storms are possible and could result in localized gusty winds and maybe some small hail. Once the line of showers/storms arrives, it should move through within 3-4 hours at each site. However, with the expected arrival time around daybreak there continues to be a chance that some renewed development could occur within the line as it traverses the area, especially south of I-80. If this occurs as guidance suggests then shower/storm activity could persist through the morning before things fully exit the area. It was for this reason that the long PROB30 was maintained, but hopefully we can refine this window as the line arrives. After the line exits the area around midday, breezy south- southwest winds will develop and persist through the afternoon. Gusts during this period look to generally be around 25 kts but locally higher gusts (upwards of 30kts) are possible. While there is still a non-zero chance (15-20%) for additional shower and/or thunderstorms to develop this afternoon, latest guidance trends have continued to back off on this scenario given that the better forcing for storms will be centered to our west in IA. That said, another round of showers and thunderstorms is expected to develop in IA this afternoon and move into northern IL and northwest IN late Monday night into Tuesday morning. Though, the coverage of these storms into our area looks much more limited (especially the thunder coverage) so have opted to introduce a PROB30 for SHRA in the 30-hour TAFs for now. Otherwise, expect VFR conditions to prevail through the period. Yack && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory until 4 AM CDT early this morning for the IL and IN nearshore waters. && $$ Visit us at weather.gov/chicago  271 FXUS64 KMOB 180846 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 346 AM CDT Mon May 18 2026 ...New UPDATE... .KEY MESSAGES... Issued at 342 AM CDT Mon May 18 2026 - A HIGH risk of rip currents is now in effect for all area beaches Tuesday afternoon. - Rain chances increase by mid to late next week, especially over the northwestern portion of the forecast area. - Localized patchy for will be possible Monday night into early Tuesday morning. && .UPDATE... Issued at 342 AM CDT Mon May 18 2026 Overall the forecast remains on track. The only change was to include a high risk of rip currents at all area beaches on Tuesday afternoon as the combination of increasing southerly flow and strong tides will likely result in dangerous rip currents at all area beaches. Conditions may quickly deteriorate during the afternoon on Tuesday as the tide begins to recede. BB-8 && .DISCUSSION... Issued at 1025 PM CDT Sun May 17 2026 Dry weather conditions generally prevail for most areas today outside of perhaps an isolated shower or storm over the interior this afternoon, best chances near the Highway 84 corridor. Rain chances gradually increase into mid and late week as upper ridging weakens and southwest flow aloft works its way into the area along with several weak shortwaves. This should be enough to generate isolated to scattered shower and thunderstorm coverage each day starting Wednesday. Rain chances continue to look like they will be best this weekend as a weak upper trough pushes across the region. Overall for those who see storms it will be a beneficial rainfall to continue chipping away at our ongoing drought across the forecast area. We will probably see some patchy fog across portions of the area through daybreak this morning and again Tuesday morning. The better signal for fog, some locally dense, appears to be Tuesday morning. Fog will generally lift pretty quickly after daybreak. Outside of the rain chances, temperatures will be warm near or just above normal for this time of year on both highs and lows throughout the week. Highs generally fall in the 85 to 90 range, warmest Wednesday where some spots across the FL panhandle into south-central AL make it to the lower 90's. Lows warm with time from upper 50's to middle 60's this morning to middle 60's to lower 70's by mid week. The rip current risk remains Moderate today, becoming High Tuesday before dropping back to a Low to Moderate risk Wednesday into late week. MM/25 && .AVIATION... (06Z TAFS) Issued at 111 AM CDT Mon May 18 2026 VFR conditions will likely give way to IFR ceilings early Monday morning. Some patchy fog may also be possible across the area. Conditions should return to VFR with a southerly wind around 10 knots gusting to around 20 knots during the day. BB-8 && .MARINE... Issued at 1156 AM CDT Sun May 17 2026 A light to occasionally moderate southeasterly flow will prevail through Thursday. Seas will build slightly by Monday and Tuesday then diminish Wednesday into Thursday. /29 && .PRELIMINARY POINT TEMPS/POPS... Mobile 83 70 87 69 / 20 10 0 0 Pensacola 82 71 84 70 / 10 0 0 0 Destin 80 71 83 70 / 10 0 10 0 Evergreen 89 65 91 67 / 30 10 20 0 Waynesboro 89 70 89 68 / 10 0 20 10 Camden 89 67 89 68 / 30 10 10 10 Crestview 88 65 91 66 / 20 0 20 0 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...High Rip Current Risk from Tuesday morning through Tuesday evening for ALZ265-266. FL...High Rip Current Risk from Tuesday morning through Tuesday evening for FLZ202-204-206. MS...None. GM...None. && $$  470 FXUS65 KRIW 180850 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 250 AM MDT Mon May 18 2026 .KEY MESSAGES... - Snow will continue to fall across the Wind River Basin, Natrona County and Sweetwater County this morning. Greatest travel impacts expected around Lander, Casper, South Pass, and over Interstate 80. Gusty winds and snow will bring reduced visibilities and possibly icy surfaces with colder temperatures moving in. Wind gusts up to 70 mph will be possible over South Pass and over Interstate 80. - Warming trend and mainly dry conditions for most of the CWA Tuesday and Wednesday with another Canadian cold front impacting the area on Thursday. This storm does not look to be as cold as the current storm. - Medium confidence for above normal temperatures returning for at least the first 2/3 of the holiday weekend. && .DISCUSSION... Issued at 240 AM MDT Mon May 18 2026 Rain changed over to snow in the Wind River Basin and across Sweetwater County just a few hours ago after 11pm Sunday night. Much of Natrona County is around 37F degrees as of 08Z (2am), with precipitation still falling as rain. The forecast remains on track this morning, with the threat of snow and wind impacting areas from South Pass southward into Sweetwater County. The 700mb low from this storm system will be passing close to the CO/WY border this morning, resulting in a tight temperature and pressure gradient. 700mb northeast winds of 50-60kt will occur from the Green Mountains/Rattlesnake Range into Sweetwater County. This will result in wind gusts of 60 to 70 mph occurring this morning over locations like South Pass down to the Rock Springs/Green River area. Windy conditions (wind gusts up to 35 mph) will be widespread across the CWA this morning as the storm system moves over CO this morning. Snowfall amounts of 2 to 6 inches is still expected across portions of Natrona County, the Lander Foothills and the eastern half of Sweetwater County. Travel conditions could be difficult this morning due to the blowing snow and icy roads. Impacts from snow accumulations on roads is likely to only last through 15Z/16Z (9am or 10am) as it will be more difficult for the snow to stick due to the high sun angle. These impacts will begin to decrease through the morning, with areas like Lander and Casper improving first as snow begins to end toward midday. Impacts along I-80 will last the longest due to the proximity of the 700mb low, but is expected to wane between 18Z and 21Z as snowfall ends. Winds will be decreasing across the area after 18Z as well, with the stronger winds of 35 to 40 mph continuing from South Pass southward into Sweetwater County and decreasing through the afternoon. Needless to say, temperatures will be anywhere from 5 to 25 degrees colder today and about 15 to 30 degrees below normal. Winds will continue to decrease this evening, as the storm system quickly exits over the Central Plains and light winds (10kt or less) expected for most areas by 06Z Tuesday. Fog development could occur as late as sunrise Tuesday morning as clouds are expected to remain in place across central and southern portions of the CWA through much of the night tonight. Dry and warming conditions are expected Tuesday and Wednesday, with another Canadian storm system impacting the area on Thursday. This system doesn't look to be as cold as today's storm and snow levels staying around 7000ft at this time. Model guidance remain split at this time, but confidence is medium for a mainly dry holiday weekend for at least 2 of the 3 days. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1000 PM MDT Sun May 17 2026 Impactful winter weather conditions will continue at Wyoming airports overnight into Monday. Locations that are currently seeing rain will likely switch over to snow after 18/0600Z, and widespread IFR conditions are forecast at many locations in central and southern Wyoming. KCOD looks to remain north of the precipitation, but showers will impact the nearby terrain. Mountain obscurations will be ubiquitous over the next 18 hours. KCPR and KLND are worth mentioning specifically for snowfall, as these locations will see snow continue into Monday evening due to favorable upslope flow. Elsewhere, snow should generally taper off during the afternoon hours Monday. Expect gusty north to northeast winds with this system, gusting in to the 20 to 30kt range for most locations. KRKS will be windiest given its position close to the storm center, so gusts will likely be higher, in the 40 to 50kt range overnight. KRKS also has a chance (40%) of morning fog on Tuesday. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 6 PM MDT this evening for WYZ002- 003-005-007>011-014-016-017-026>029. Winter Storm Warning until 6 PM MDT this evening for WYZ015- 018>020-022-030. && $$ DISCUSSION...LaVoie AVIATION...VandenBoogart  753 FXUS63 KBIS 180857 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 357 AM CDT Mon May 18 2026 .KEY MESSAGES... - Medium to high chances (40 to 80 percent) for showers this afternoon through this evening south central and into the James River Valley, low chances elsewhere. - Cold overnight low temperatures near or slightly below freezing tonight (west and north central), and Tuesday night (southwest, central, and east). - Temperatures warming back to above normal by late in the work week and for the weekend, with near daily chances for showers and a few thunderstorms. && .DISCUSSION... Issued at 357 AM CDT Mon May 18 2026 Upper level trough will push across the state later today bringing the next round of showers. Before doing so, lingering low level moisture will bring abundant cloud cover and cooler temperatures this morning through today. A few rain showers and pockets of drizzle will also be found this morning, along with some patchy fog, as a result of this lingering low level moisture. An increased gradient on the surface of the exiting surface low may also bring some breezy north winds today to southern and eastern portions. Temperatures today will be quite cool and generally in the 40s, with some lower 50s. Later today through this evening, the mentioned upper level wave will move through bringing more organized showers to the state. Best chances for these showers remain across south central and eastern portions of the state where the better synoptic lift is. Isolated to perhaps scattered showers are possible elsewhere. QPF will be much less from this second wave, with the higher amounts being a tenth to a quarter of an inch in the southeast. The mentioned wave moves eastward tonight, although a few showers may linger as it does so especially in the west. Perhaps a rain snow mix is possible from these lingering showers. Cooler temperatures will also be found tonight with lows in the 30s. Depending if clouds can clear, some frost is possible. Low level moisture looks to linger, although some far western portions could at least partially clear which may be the area to monitor tonight for frost. Although not in the forecast, perhaps some patchy fog is also possible tonight into Tuesday morning with light winds and lingering low level moisture. Surface high will push this low level moisture eastward on Tuesday. Some isolated showers are possible in the morning as it does so, then look for clearing skies and slightly warmer temperatures in the 50s. Breezy northwest winds could also linger in the east for Tuesday. This surface high combined with ridging aloft will bring clearing skies tonight and colder temperatures. Most areas are forecast in the 30s, with some areas in the central and east could see temperatures near to slightly below freezing. Widespread frost is still likely, with perhaps some freeze highlights also needed. There still remains some uncertainty if we fully clear out and if a switch to a breezy southerly flow occurs overnight. Will continue to message the cold temperatures, yet hold off on any highlights at this time for Tuesday night into Wednesday morning. A breezy southerly flow is then forecast for Wednesday, with another broad trough pattern approaching the state. Warmer temperatures will return as a result with highs forecast in the 70s. Some lower RH values may also return, although recent rainfall should help with fuels. This trough pattern could also bring some isolated to scattered showers and thunderstorms in the afternoon and evening for Wednesday. Broad trough pattern then looks to continue through the end of the upcoming week. This is forecast to bring seasonable temperatures and near daily chances for showers and thunderstorms. Instability looks limited during the workweek, thus the chances for severe thunderstorms looks low at this time. Daily high temperatures in the 60s with lows in the upper 30s to mid 40s are also expected, limiting the frost and freeze threat for the end of the week. Warmer temperatures are then possible for the upcoming weekend with highs in the 70s Saturday to perhaps near 80 on Sunday. Current NBM chances for precipitation this coming weekend are low, although zonal flow aloft and some weak instability could change this with each forecast update. These warming temperatures could also bring lower RH values in the afternoon this weekend. Winds generally look light, which should limit the fire weather threat. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1245 AM CDT Mon May 18 2026 Low clouds will linger tonight and through much of the day Monday, bringing MVFR to periods of IFR ceilings. Some patchy fog along with isolated to scattered rain/drizzle can also be expected tonight into Monday morning, bringing more IFR to perhaps LIFR conditions. Shower activity is then more confined to the south and east Monday through Monday evening, although most sites will have at least slight chances for rain showers. Any shower has the potential to bring MVFR to IFR conditions. Monday night will see shower activity diminish, although low clouds could linger bringing MVFR to isolated IFR ceilings. A breezy north wind may also be found throughout the forecast period. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Anglin AVIATION...Anglin  755 FXUS65 KBOI 180857 AFDBOI Area Forecast Discussion National Weather Service Boise ID 257 AM MDT Mon May 18 2026 .KEY MESSAGES... - Mountain showers on Monday, otherwise dry, breezy and slightly warmer. - Dry with temperatures warming back above normal starting on Wednesday. && .SHORT TERM /Through Wednesday Night/... The tight surface pressure gradient behind an eastward exiting low pressure system will continue to generate breezy northwest winds today across much of the area. Wind gusts between 25 and 35 mph can be expected this afternoon, though they will not be quite as strong as what was observed on Sunday. While a stable air mass dominates the lower elevations, lingering afternoon instability will support a slight chance of light showers over the mountains today, with minimal accumulation expected. Northwest flow aloft will carry into Tuesday as high pressure builds over the Pacific. A more stable and dry air mass will keep conditions clear across the region, allowing temperatures to warm back to near normal values for this time of year. By Wednesday, an embedded shortwave trough will move through the intermountain west, tracking across our area into Wednesday night. This system will bring an increase in cloud cover along with light, isolated showers primarily focused across the West Central Mountains of Idaho. The arrival of this shortwave and its associated cloud cover will also work to slow down the overall warming trend as we transition into the long term period. && .LONG TERM /Thursday through Monday/... A trough over Montana will dig into southern Idaho on Thursday, bringing cooler temperatures and a slight chance of high terrain showers (10-20% chance). This trough will quickly move east on Friday, bringing a return to dry northwest flow through Saturday with temperatures 5-10 degrees above normal. A weak shortwave passage will bring another low chance of showers over high terrain late Saturday into Sunday, but forecast confidence is very low. By Sunday, a ridge of high pressure will build into the region, bringing warm and dry conditions ahead of a strong upper level low diving down off the British Columbia coast. Models diverge substantially on the path of this upper level low early next week, with some members (ECMWF) bringing this low directly over the region by Monday evening. Current forecast does not favor this outcome, with a strong bias towards the warm and dry scenario on Monday. && .AVIATION /06Z Monday through Tuesday/... Issued 1155 PM MDT SUN MAY 17 2026 Generally VFR. Patchy fog/stratus in sheltered mtn valleys through morning. Scattered showers redevelop Monday PM across E Oregon and mtns of SW Idaho. Brief MVFR/IFR and obscuration in mtn precip. Monday snow levels: 5500-6500 ft MSL. Surface winds: W-N 10-20 kt with areas of gusts to 20-25 kt. Winds aloft at 10kft MSL: N-NE 20- 35 kt. KBOI...VFR. Foothill showers return Monday PM. Surface winds: W-NW 5- 15 kt overnight, then NW 10-18 kt with gusts around 25 kt after Mon/16Z. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Freeze Warning until 8 AM MDT this morning for IDZ016. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...JDS LONG TERM....SA AVIATION.....SA  762 FXUS65 KCYS 180857 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 257 AM MDT Mon May 18 2026 .KEY MESSAGES... - Accumulating snow through Monday afternoon with Winter Storm Warnings for many of our high elevation and mountain zones and Winter Weather Advisories for nearby zones. - Near record cold Monday and Monday night will lead to widespread freezing temperatures, which may damage sensitive vegetation and outdoor irrigation systems. - Slow warming trend by the mid to late week with temperatures near normal by Thursday and Friday. Chance of showers and a slight chance of thunderstorms each day through Friday evening. && .SHORT TERM /THROUGH TUESDAY/... Issued at 255 AM MDT Mon May 18 2026 Late season winter storm ongoing across southeast Wyoming with everywhere above 6500 feet changing to snow within the last 3 hours. Rain/snow line is roughly 10 miles west of Cheyenne at this hour based on area webcams which show snowfall at the Warren Exchange along I-80. Most of Interstate 80 west of there shows very difficult travel conditions with some of the worst conditions on the I-80 Summit, which is currently experiencing visibility below one half mile in heavy snow. Snow is starting to accumulate on the roads above 7000 feet and expect this to continue through much Monday morning. Storm system is just starting to intensify at this hour...as seen by the current IR Satellite loop with cooling cloud tops over most of Wyoming and the distinct "comma cloud" beginning to take shape. No changes yet to Winter Weather headlines, but will need to keep a close eye on the I-25 corridor, the Pine Ridge, and the higher hills around Scottsbluff and Banner county for potential extensions this morning. Thankfully, even if snowfall rates become an issue, snow will struggle to stick on the pavement shortly after sunrise. Snow will be ongoing as we head into this afternoon, although with the high May sun angle impacts should be limited with melting on area roadways. Snowfall rates will begin to ease down during the middle of the afternoon as the best dynamic forcing shifts east into the high plains. Some rain/snow mix expected down to 4500 to 5000 feet, but little in the way of accumulations since this will occur during the daytime hours. Remnant snow (or rain/snow mix below 5000 feet) will taper off and finally end by midnight tonight as the storm system transitions to an open wave trough and rapidly ejects northeast. Once all is said and done, this system should provide much needed moisture to the area with around a half inch of precip for the eastern plains, and close to 1.00 inch to as high as 1.50 inches for southeast Wyoming. Main forecast concern after today will be how quickly we clear out at night. There is increasing confidence that a good part of the eastern plains with clear out by daybreak Tuesday with portions of Carbon county below 50% cloud cover as well. A hard freeze is expected late tonight through most of Tuesday morning, with freezing temperatures likely lasting until shortly before noon in portions of the forecast area. This is due to a record breaking unseasonably cold airmass behind the main storm system, which is forecast to settle over the area today. Current 10th to 25th percentile low temperatures tonight are between 14 to 20 degrees over most of the high valleys in southeast Wyoming, with 17 to 27 degrees across the eastern plains. Upgraded the Freeze Watch to a Freeze Warning for east central Wyoming and far northwestern Nebraska since these are the most likely zones to see clearing skies earlier in the night. Kept the Watch going for the remainder of the area, but mainly to see how this current storm system and potential snowfall pans out first. Conditions will improve a little on Tuesday with 700mb temperatures between -2c to -5c under northwest flow. High temperatures will be warmest where there is no snow pack...mainly over far eastern Wyoming and western Nebraska with highs in the 50s to low 60s. Further west, expect highs to generally be in the 40s and even upper 30s in areas with the deepest snow pack. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Issued at 230 PM MDT Sun May 17 2026 Certainly less active than the short term, but the long term period will still have some impacts. We will likely dip below freezing again on Tuesday night especially in regions that don't melt away all of their snow (i.e. areas west of the I-25 corridor). On Wednesday, temperatures will gradually moderate into the upper 50s to near 60 east of the Laramie Range and upper 40s to lower 50s west given weak isentropic ascent/warm advection as the longwave trough responsible for our anomalously cool weather dampens. There may be enough lingering moisture for a few showers and thunderstorms primarily over the higher terrain, however probabilities of seeing QPF > 0.05" are running at about 25%, so any moisture is unlikely to be beneficial. Given dry boundary layers as shown on model forecast soundings show a very dry boundary layer with surface dewpoint depressions exceeding 40 degrees, showers and thunderstorms will likely produce far more wind than rain. Temperatures gradually warm on Thursday and Friday as a series of shortwave troughs embedded in quasi-zonal flow traverse across Eastern Wyoming and Western Nebraska, leaving in low (30%) chances for high-based showers and thunderstorms. Highs will gradually increase to climatological values (mid-upper 60s for Cheyenne to near 70 for the Nebraska Panhandle). Heading into the weekend, we will begin to dry out and encounter a faster warming trend to above- average temperatures as weak mid-level ridging establishes itself over the Rocky Mountain West, with no widespread or beneficial precipitation chances in sight. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1153 PM MDT Sun May 17 2026 Aviation trends over the next 12 hours will consist of deteriorating conditions as a winter system pushes into the area. Rain will transition to snow at southeast Wyoming terminals, causing visibility reductions and low CIGs. Windy conditions around KRWL could also lead to areas of blowing snow, further reducing visibility. Western Nebraska terminals will primarily see rain, however low CIGs will likely develop during the morning hours. Snow will continue through the day at southeast Wyoming terminals, so IFR conditions are expected through much of the TAF period. MVFR conditions are more likely at Nebraska terminals for the first part of the day, with CIGs continuing to lower through the afternoon to IFR criteria. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Freeze Watch from late tonight through Tuesday morning for WYZ106-113-115>119. Freeze Warning from 8 PM this evening to 10 AM MDT Tuesday for WYZ101-102-107-108. Winter Weather Advisory until 6 PM MDT this evening for WYZ101- 105-106-111-115-117. Freeze Warning from 5 AM to 10 AM MDT this morning for WYZ102. Winter Storm Warning until 6 PM MDT this evening for WYZ103- 104-109-110-112-114-116. Freeze Watch from this evening through Tuesday morning for WYZ104-105-109>111. NE...Freeze Watch from late tonight through Tuesday morning for NEZ002-003-020-021-054-055. Freeze Warning from 8 PM this evening to 10 AM MDT Tuesday for NEZ019-095-096. && $$ SHORT TERM...TJT LONG TERM...NB AVIATION...SF