FXUS61 KLWX 090801 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 401 AM EDT Thu Jul 9 2026 .WHAT HAS CHANGED... Flood Watches have been issued for the threat of flash flooding. This is for the 2 PM to 11 PM timeframe which covers much of the I-95 corridor back into the north-central Maryland and northern Virginia. && .KEY MESSAGES... - 1) Thunderstorms, some of which may produce damaging winds and heavy rain, are possible through Friday. - 2) Turning cooler this weekend into Monday, with renewed heat by mid-week. && .DISCUSSION... KEY MESSAGE 1...Thunderstorms, some of which may produce damaging winds and heavy rain, are possible through Friday. The early morning surface analysis places a wavy frontal zone across southern North Carolina up across the central Appalachians. To the north of this boundary, a light southeasterly wind is being observed over the local area. Skies generally remain mostly cloudy with temperatures in the low/mid 70s, with dew points staying around the low 70s. The thermodynamic environment remains unstable aloft with most unstable CAPE (MUCAPE) averaging around 1,000 J/kg, without any inhibition. Consequently, spotty showers and a few thunderstorms continue to spawn early this morning. In areas not seeing shower activity, low stratus and patchy fog have begun to materialize. This overall pattern largely sticks around through the early/mid morning hours. Expect these low clouds to linger throughout the morning before breaks in the overcast skies occurs by the midday hours. At the same time, the surface boundary to the south surges poleward as a warm front. The other key player is a seasonably strong shortwave currently along the Indiana/Ohio border down into the Tennessee Valley. This trough is forecast to move toward the Mid-Atlantic states which is accompanied by increasing mid-level winds to around 30 to 35 knots. Ultimately this bolters 0-6 km vertical shear to 30 knots which is plenty sufficient for early/mid July standards. The Storm Prediction Center currently has a Slight Risk mainly from U.S. 15 eastward. While instability is not off the charts, mixed-layer CAPE values rise to around 1,500 to 2,000 J/kg. The tropical air mass featuring 2 to 2.25 inch precipitable water values will lower lifted condensation levels (LCLs). This ultimately puts a cap on the amount of downdraft CAPE (DCAPE), generally averaging around 600 to 800 J/kg. The 00Z high- resolution model suite indicates convective initation off the higher terrain during the early morning hours. High-resolution ensembles depict 40 dbZ paintballs which track toward the I-95 corridor during the late afternoon/early evening hours. Ample vertical shear will aid in decent storm organization, particularly for developing line segments. As usual, damaging wind gusts should be the primary severe hazard, but with frequent lightning and torrential downpours possible in any storm. The primary threat for severe thunderstorms ends by the mid-evening hours as convection pushes out to the Eastern Shore. With only modest DCAPE values on forecast soundings, the forward acceleration of storms via cold pools/gust fronts may not offset a possible flash flood threat. In particular, locations recently hit by recent heavy rainfall along with the more vulnerable I-95 urban areas will see an elevated flood risk. The Weather Prediction Center has placed a Slight Risk across all areas north of I-64. Given a decent signal for heavy rainfall along the I-95 corridor, have opted for a Flood Watch given the threat of flash flooding. This covers the 2 PM through 11 PM timeframe while spanning north-central Maryland down to northern Virginia and points eastward. While convection should be progressive in nature, intense rainfall rates on the order of 2 to 3 inches per hour could aid in some hydrologic response. Will continue to monitor for any necessary westward/southward expansions. Some degree of convective threat likely continues into Friday given ample moisture in the atmosphere. However, a primarily westerly flow often is known to negate the development of more organized thunderstorm activity. Friday does mark the warmest day of the remainder of the week with highs in the upper 80s to low 90s. Depending on how much rainfall occurs during the previous day, some level of flash flood risk may take place again on Friday afternoon/evening. KEY MESSAGE 2...Turning cooler this weekend into Monday, with renewed heat by mid-week. As an upper ridge builds across the Desert Southwest into the central Rockies, this will lend itself to longwave troughing across far eastern Canada into the northeastern U.S. Weak height falls accompanying this trough will push a cold front through the area on Saturday morning. This boundary sags southward in time as broad high pressure over the Great Lakes and New England approaches from the north. Some lingering showers are possible over the weekend given the close proximity of the frontal zone to the area. Temperatures drop over the weekend with initial post-frontal northwesterlies giving way to easterlies by Sunday. The true drop in humidity levels does not take place until late in the weekend into Monday. This should offer a dry start to the upcoming work week. Eventually above average temperatures return to the picture toward the middle of next week. Building heights across the central U.S. should eventually spread eastward into the Great Lakes and Ohio Valley. Low to mid 90s become more likely as this occurs, but with less humidity than the last bout of excessive heat. Forecast dew points are in the 60s with upper ridging generally limiting convective chances. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... Like the preceding night, low-level moisture being trapped in the nocturnal boundary layer has lowered ceilings to MVFR. In some spots, the low clouds have been slower to respond to the moist low-levels in the atmosphere. This is likely due to a bit of lingering wind. Will continue to show a mixture of IFR to near IFR ceilings across all TAF sites through the mid/late morning hours. However, these low stratus should gradually mix out by midday ahead of another active weather day. As a seasonably strong shortwave moves through this afternoon, the models agree on numerous showers and thunderstorms pushing eastward across the area. Have maintained a TEMPO group in the 3 to 7 PM timeframe, slightly earlier for the western terminals. Restrictions are likely as these storms roll through, some of which could be severe in nature. In the wake of these storms, initial southerly winds turn more southwest to westerly tonight. Low ceilings are again possible, particularly in areas which saw heavier rainfall. Westerly winds on Friday may offset some of the convective threat on Friday. However, some afternoon to evening restrictions will again be possible. A cold front moves through on Saturday which yields a shift to northwesterly winds. These eventually turn more easterly on Sunday into Monday as the boundary slides farther to the south. Despite some weekend shower chances, mainly VFR conditions are expected. && .MARINE... With summertime gradients in place, any potential for Small Craft Advisories appears low through the weekend and into early next week. Any hazardous conditions over the waterways will again be tied to thunderstorms, lightning, and any gust fronts/outflows. Special Marine Warnings may be needed for this afternoon and evening as strong convection pushes eastward to the I-95 metro areas. While westerly winds should offset some of Friday's convective threat, some storms could impact the waters during the core heating hours. && .TIDES/COASTAL FLOODING... Anomalies are around 1 to 1.25 feet early this morning as winds have shifted over to southerly. This will likely result in near minor flooding of vulnerable shoreline through the end of the week. Annapolis is most likely to reach the minor flood threshold, and a Coastal Flood Advisory has been issued for the early morning high tide. Havre de Grace will also be close. A gradual decline in water levels is expected this weekend. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Flood Watch from 2 PM EDT this afternoon through this evening for DCZ001. MD...Flood Watch from 2 PM EDT this afternoon through this evening for MDZ004>006-008-011-013-014-503>508. Coastal Flood Advisory until 4 AM EDT early this morning for MDZ014. VA...Flood Watch from 2 PM EDT this afternoon through this evening for VAZ053-054-505-506-526-527. WV...None. MARINE...Flood Watch from 2 PM EDT this afternoon through this evening for ANZ530. && $$ DISCUSSION...BRO AVIATION...BRO MARINE...BRO