917 FXAK68 PAFC 220125 AFDAFC Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 525 PM AKDT Fri Aug 21 2026 .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Today through Sunday)... A vertically stacked low located just south of Prince William Sound continues to weaken as it lifts inland to the northwest. Behind this system a transient ridge drifts overhead tonight. As a result, shower coverage has diminished across much of Southcentral, with many areas seeing sunshine. Despite this ridge, some isolated showers may linger in spots tonight, particularly for mountainous and coastal areas. However, this period of improved weather won't persist, as another shortwave trough moving over Southwest Alaska pushes into Southcentral by Saturday morning. This will cause rain showers to fill into most areas by mid-to-late morning tomorrow. The Western Susitna Valley will likely be a hot-spot for precipitation, given strong moisture advection off of the Cook Inlet, as well as typical coastal areas along the Kenai Peninsula and Prince William Sound. Southeasterly downsloping flow off the Chugach Range will suppress precipitation in and around Anchorage, though southeasterly winds will result in gusty winds across the Anchorage Hillside and the south side of town. The Copper River Basin will remain mostly dry with some breezy southeast winds tomorrow afternoon. Steady rain will taper off this evening as the upper trough closes off into surface low and ejects into the Gulf. Strong northerly flow will develop behind this system, causing gusty northerly winds in Seward and easterly winds in Whittier through tomorrow morning. Sunday will finally provide a break from the active weather as broader ridge fills in across the western mainland. This feature will filter in much drier air across the region, causing any lingering showers to fizzle out by noon. This will make way for sunshine and warmer temps across the region. However, patchy fog may be possible early Sunday morning for Anchorage, the Kenai Peninsula, and the Susitna Valley as skies quickly clear out. -CW && .SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days 1 through 3: Today through Monday)... An active weather pattern continues through Monday as a series of lows and associated upper-level shortwaves move across the Bering Sea and Southwest Alaska. The first system will gradually weaken as it moves inland, while another stronger system develops over the western Bering and track eastward through the weekend. The first surface low continues to move inland across western Alaska Saturday as its associated upper-level trough progresses eastward. Steady rain will gradually taper from west to east through Saturday, though showers will linger across portions of Southwest Alaska behind the departing system. Winds will also diminish as the low weakens inland, with the strongest winds shifting away from the eastern Bering and Southwest coast. Attention then turns to the next system developing over the western Bering Saturday. A shortwave lifting out of the North Pacific will interact with another disturbance moving east from Kamchatka, allowing a surface low to organize and strengthen as it tracks northeastward across the Bering. An unstable air mass accompanying the system may support a slight chance of thunderstorms over portions of the western Aleutians Saturday before convection diminishes. By Sunday, the surface low and associated upper-level circulation become better organized over the Bering Sea. The tightening pressure gradient will support increasing southerly to southwesterly winds across much of the Bering and Aleutians, with widespread small-craft and areas of gale-force winds possible. Rain spreads eastward across the Bering and reaches the Southwest Alaska coast Sunday before pushing farther inland Sunday night. Sunday night into Monday, the upper-level low continues to deepen while lifting northward toward the Bering Strait and western Alaska. Meanwhile, a strong shortwave rotates around the southern and eastern side of the circulation and moves into Southwest Alaska. This will keep unsettled conditions in place through Monday, with periods of rain continuing across much of Southwest Alaska and showers persisting across the Bering and Aleutians. Gusty southerly to southwesterly winds will also continue across portions of the Bering and Southwest coast before gradually easing as the system shifts northward. Overall, the progressive and active pattern continues through Monday, with additional systems remaining over the North Pacific and Bering Sea. Forecast details, particularly the strength and track of the Sunday-Monday system and associated winds, will continue to be refined as model agreement improves. LM && .LONG TERM FORECAST (Days 4 through 7: Tuesday through Friday)... The pattern appears to remain active through the long-term period over much of Southern Alaska. A relatively strong low pressure system over the northern Bering Sea will exit to the northeast into the Western Alaska mainland, but push a front through Southwest and potentially Southcentral Alaska early next week. By Tuesday, largely zonal flow establishes over much of the Bering Sea, allowing for relatively less impactful conditions in the area. By Wednesday morning, model solutions continue to diverge, and while both ECMWF and GFS advertise a low entering the southwestern Bering Sea, the EC shows a stronger low moving in, bringing stronger winds and precipitation core dragged in from the northern Pacific. The GFS solution is much more muted, with a weak low pressure system, loose pressure gradients, favoring weaker winds and lighter precipitation across the Western Aleutians. GFS and EC however are more progressive, bringing the low into the northwestern Bering by Thursday morning, with the Canadian solution lagging the low still in the southwest Bering, over the Western Aleutians. By Friday, agreement improves between model solutions, with fair agreement that the low moves into the eastern Bering, with all solutions also bringing the low's depth more in- line, and the low center over the Kuskokwim Delta/Mekoryuk Island. -CL && .AVIATION... PANC...VFR conditions with intermittent rain showers and ceilings near or above 5000 ft will prevail. Slight chance of very briefly dropping to MVFR conditions during any locally heavier rain showers. There is also a slight chance of a low stratus deck moving in by 12z. Light winds will persist. && $$  259 FXUS63 KFSD 220133 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 833 PM CDT Fri Aug 21 2026 .KEY MESSAGES... - Low chances (less than 20%) for showers and storms into tonight along and south of the Missouri River. Severe weather risk is low. - Slightly cooler weather for the weekend. Saturday should remain dry with rain chances (40-70%) returning to portions of the area by Sunday morning. Rainfall amounts could exceed a tenth of an inch. - Additional chances for rain, and potentially strong to severe thunderstorms (5-15%), are possible through next week. Details are uncertain, so continue to check the latest forecast for the most up to date information. && .UPDATE... Issued at 831 PM CDT Fri Aug 21 2026 No major changes to the forecast for tonight and tomorrow. A weak boundary heading towards I-90 has set off a few showers and storms as it moves southward, mainly over southwest Minnesota and far eastern South Dakota. Should see this continue weakening with southeastward extent as we lose daytime heating. Meager instability is in place, so just expecting weak thunderstorms with brief downpours and some lightning over roughly the next hour. Higher instability values (2,000+ J/kg of MUCAPE) are located near and south of the Missouri River, but this will slowly sag southward through tonight, though some guidance keeps around 1,000- 1,500 J/kg in place over Gregory County through the early morning hours. With the better lift to the south of the area, thunderstorms are unlikely. If a storm were clip our area, severe weather is unlikely as skinny CAPE profiles would really hinder the development of any large hailstones and the elevated nature of any storm would preclude a damaging wind threat. Any storms will be well south of the area by sunrise Saturday, leading a warm and pleasant late summer day! && .DISCUSSION... Issued at 139 PM CDT Fri Aug 21 2026 Quiet conditions persist this afternoon as temperatures have warmed to the 70s and 80s across the area. Quiet conditions are expected to continue for the rest of the day as the cold front has fully pushed through the area. This will keep storm chances south and west of the forecast area. Can't rule out the low possibility (less than 20%) of a shower or weak storm passing along and south of the Missouri River this afternoon, evening, and potentially into the overnight hours. Should this occur, the chance for a severe storm is low. Surface ridging will begin to slide into the forecast area tonight, resulting in light and variable winds with lows falling to the upper 50s to low 60s. Patchy fog is again on the table but with drier air in place, think that any fog that does develop will once again be tied to a few river valley's. Saturday begins the weekend on the quiet side as high pressure pushes through the Northern Plains. High temperatures will be a bit cooler in the upper 70s to low to mid 80s, with a continuation of light northerly winds. This will make for a wonderful Saturday, perfect for outdoor activities! Rain chances will increase late Saturday night through Sunday as a weak shortwave trough rounds the top of a building upper level ridge. This will result in increasing chances for rain across the area for the day on Sunday. Cloud cover with the associated chances for rain will keep high temperatures a bit cooler in the upper 70s to low 80s. While some showers are possible during the morning timeframe, the highest chances for rain will come Sunday evening and night as the main shortwave pushes through the area. The ensembles show a broad 40-70% chance for rainfall totals to exceed a tenth of an inch. Soundings show some elevated instability in place so thunderstorms are possible, though severe storms are not expected at this time due to weak shear profiles. With non-severe storms on the table, rainfall amounts could be locally higher depending on how storms track. An active pattern continues aloft for next week. Medium range guidance shows shortwave troughs continuing to push through the Northern Plains within the northwest flow regime. This will lead to chances for rain almost every day next week. However, the ensembles show a large variance in rainfall probabilities due to the differences in these upper level features. Latest machine learning (ML) guidance does show low probabilities (5-15%) for severe weather throughout the week. Details for severe weather remains uncertain so continue to check the forecast for the most up to date information. Aside from rain and storm chances, high temperatures look to remain in the upper 70s and 80s. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 628 PM CDT Fri Aug 21 2026 VFR conditions expected through the period. A few showers and a thunderstorm or two is moving towards the Highway 14 corridor early this evening, but should generally weaken as it moves southward. Very small chance (<20%) of a shower or a stronger storm for the Missouri River Valley and points south through tonight. No impacts expected to the TAF sites. Winds will be generally light and variable through the period, though winds could pick up from time to time out of the north-northeast around 5-10 kts during the day Saturday. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ UPDATE...Samet DISCUSSION...Meyers AVIATION...Samet  227 FXUS63 KIND 220159 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 959 PM EDT Fri Aug 21 2026 .KEY MESSAGES... - Isolated/scattered showers and a few t-storms are possible late tonight...and again Saturday afternoon, mainly east. - Cooler and less humid weather expected Sunday through Tuesday with highs mainly in the 70s to near 80. - Areas of late night/early morning fog will occur Saturday and Sunday nights. - Dry weather expected Monday and Tuesday with increasing chances for rain and storms mid-late next week. && .FORECAST UPDATE... Issued at 959 PM EDT Fri Aug 21 2026 Fair conditions will continue this evening amid weak surface high pressure departing under increasing clouds coming off upstream convection. Approaching supporting wave will bring increasing chances of RWs and embedded isolated thunder...granted any cells are expected to be weaker than present activity over northern Illinois, with possibly a stray strong/marginally severe wind gust near/west of Lafayette during the early overnight. Otherwise widely scattered showers to cross much of the region while overall dissipating into pre-dawn hours. Although better chances of modest regeneration across northern counties which will be closer to vort support...and low-moderate chances of a few additional showers towards dawn near the cold front entering the CWA's northwestern corner. Cannot rule out patchy visibility reductions from fog. Tonight will be the last period with overall light, if not variable winds. Low temperatures to display a modest range given overnight cloud cover, from low 60s near Muncie to 66 in Vincennes. && .DISCUSSION (This evening through Friday)... Issued at 318 PM EDT Fri Aug 21 2026 Late this Afternoon... Elevated showers over northern Indiana are indicative of a weak lead shortwave. An instability axis extends across far eastern portions of the forecast area northward into NE Indiana. Recent convective development in NE Indiana was occurring in a zone of modest low level convergence. There is a small chance that an isolated shower or TS will develop in extreme northeastern zones before activity weakens around sunset. Tonight and Saturday... Vigorous convective development will continue to the northwest of central Indiana across parts of southern WI/far northern IL and eastern IA the remainder of the afternoon into the evening. This activity is forming in a broad convergence zone ahead of a seasonably strong shortwave trough and within a moderate to strong instability axis with MLCAPE values from 2000-3000 J/KG. TS activity in several lines will develop develop S-SE towards central Indiana overnight. However, instability decreases markedly with SE extent, with MUCAPE under 1000 J/KG across all of central Indiana overnight. Time of day combined with minimal instability suggests that the severe weather threat is close to zero across the forecast area. Well south of any precip and/or convective clouds overnight, patchy fog is expected across southern portions of central Indiana where light winds and mostly clear skies will prevail. The weak cold front associated with this progressive system will push across the region Saturday morning. There is some indications that a secondary shear induced mid level vorticity max will move through the region on Saturday afternoon. With residual instability, a few lower topped showers/TS will be possible behind the main cold front but ahead of this mid level feature/surface convergence boundary during the afternoon, mainly over eastern zones. Have maintained pops in these regions. Would not be overly surprised with some renegade showers across western zones where some instability remains, but for the sake of consistency will leave out of theforecast. Saturday night through Sunday... In the wake of the shortwave/cold front Saturday surface high pressure will gradually build southward through the northern/central plains into the upper MS valley. Broad NW low level flow will support some lake enhanced clouds and showers Saturday evening and again during Sunday afternoon in far northern areas mainly during the period when daytime heating/convective overturning is maximized. A stout mid level inversion noted on forecast soundings should limit convective cloud depth and only a slight chance of showers is currently forecast. Sunday night through Tuesday... Broad area of surface high pressure will push SE into the Ohio Valley through the period, providing for much drier conditions, with dewpts falling into the 50s. As a result most areas will see low temperatures in the 50s Sunday night. Light winds and mostly clear skies will lead to another night with areas of fog Sunday night. A weak system in the NW flow aloft is expected to move across the MO/mid-MS valleys Monday into Tuesday. At present the only expected effect from this system will be increasing mid-high clouds. This should limit fog chances Monday night and keep high temperatures in the 70s most areas Monday and Tuesday. Wednesday through Friday... Another upper wave/surface cold front will move through during the period. Confidence in timing is very low considering the system is currently off the west coast, so for now will only have some low PoPs. Seasonable temperatures are expected with increasing humidity with increasing SW flow in the low levels. && .AVIATION (00Z TAF Issuance)... Issued at 748 PM EDT Fri Aug 21 2026 Impacts: - Isolated/scattered -SHRA/TSRA late tonight into Saturday morning - Low chance for brief fog at outlying sites Saturday morning - WNW winds gusting up to 20-25KT Saturday afternoon/late day Discussion: Mainly VFR conditions expected near central Indiana terminals through Saturday evening. Area of BKN/OVC mid cloud coming off of northern IL convection will overtake western central IN by 02Z this evening, ahead of approaching considerable cloudiness from next, weaker, upper wave/cold front. At times scattered convection and possible isolated thunder, will cross local region within 06Z-13Z, with additional -SHRA possible with fropa early Saturday. Low confidence on MVFR from convection...with also a brief window of potential MVFR from fog at terminals outside of KIND, towards dawn. Overall light/variable flow tonight will yield to stronger post- frontal flow Saturday midday-afternoon, with winds veering slightly within 270-320 degrees, gusting up to 20-25KT through late afternoon. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ UPDATE...AGM AVIATION...AGM DISCUSSION...Crosbie