Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
677 FXUS61 KLWX 111345 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 945 AM EDT Mon Aug 11 2025 .SYNOPSIS... Warm temperatures, mostly dry conditions, and low humidity look to continue through Tuesday as broad high pressure remains nearby. A frontal system may gradually approach from the west Wednesday into Thursday as the high moves out to sea. This will result in increasing heat and humidity as well as thunderstorm chances across the region later in the workweek and into the upcoming weekend. && .NEAR TERM /THROUGH TONIGHT/... High pressure off the Northeast and Mid-Atlantic coast will continue an eastward drift out to sea today. Return flow around the departing high will result in an increase in heat and humidity. For areas east of the Blue Ridge, a low stratus deck has persisted this morning within a light onshore flow regime. Based on the 12Z IAD sounding, the depth of moisture is quite shallow, generally running around 500 m (just over 1,500 feet). However, this should eventually disperse in the next hour or two which will result in a partly to mostly sunny afternoon. With the increase in heat and humidity and a bit of a breakdown to the ridging aloft will come the potential for a pop up shower or thunderstorm or two. This potential is highest furthest from the departing ridge, generally from southern MD across the central VA Piedmont into the central Shenandoah Valley. Forecast high temperatures will be mid 80s to near 90 degrees, with 70s to low 80s across the mountains. Another round of low clouds and patchy fog is possible in continued onshore flow tonight. It will be noticeably more humid with low temperatures in the 60s to lower 70s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Heat and humidity will continue to increase Tuesday into Wednesday. Shower and thunderstorm chances are a bit higher Tuesday afternoon and extend a bit further north and east when compared to Monday, but lingering ridging should keep coverage scattered. High temperatures will likely eclipse 90 for much of the area, and when combined with dew points around 70 could result in heat index values of 95-100. More expansive storm probabilities are noted on Wednesday as an upper trough swings by to the northwest and its associated surface cold front drifts toward the area. Wednesday currently looks like the hottest day of the upcoming week - generally lower 90s with heat index values around or a little over 100 (though some of this could be muted by shower and thunderstorm activity). && .LONG TERM /THURSDAY THROUGH MONDAY/... A summertime pattern persists through the period with heat, humidity, and daily chances for showers and thunderstorms in the forecast. On Thursday, a rather potent longwave trough crosses through Quebec while the attendant height falls graze the northeastern U.S. In the wake, global ensembles show a subtropical ridge across the southeastern U.S. strengthening and expanding in time. 500-mb heights push back into the 589-592 dm range as the influence of northern stream disturbances wanes. While the initial longwave trough carries a cold front on the doorstep of the local area, the boundary should stall nearby on Friday before completely shearing out over the weekend. Daily high temperatures should push into the mid 80s to low 90s, with mountain locales seeing mainly 70s to low 80s. Given the return of the humidity, overnight lows will not plunge the way they have been over the past week or so. Expect most to fall into the upper 60s to low 70s, with some low/mid 60s across the mountains. The best chance for showers and thunderstorms would be Thursday and Friday with the cold front stalling nearby. Thereafter, the further building of heights and lack of any frontal zones leads to decreasing convective chances for the weekend. However, in these scenarios, mesoscale boundaries like bay/river breezes and terrain circulations can act as a focus for some afternoon/evening convection. The Climate Prediction Center outlook into next week favors a continued summertime pattern with above average temperatures being favored. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... As model guidance had suggested, low clouds remain banked up against/east of the Blue Ridge this morning. With the current satellite appearance and continued low-level saturation, these clouds may linger though late morning or midday. The IFR/MVFR ceilings should gradually lift/scatter by 14z-16z. A pop up shower or thunderstorm can`t be ruled out this afternoon near KCHO. S/SE flow AOB 10 kts is expected. Low clouds and/or fog appear likely again late tonight into Tuesday morning, with a bit higher chances for PM TS mainly near KCHO and KMRB Tuesday afternoon. More numerous TS are possible Wednesday afternoon. Winds will be S/SW AOB 10 kts. With a frontal zone nearby, there will be a risk of daily afternoon/evening showers and thunderstorms Thu/Fri. Thus, some restrictions cannot be ruled out at times across all terminals. Gradients remain on the weaker side with mainly northwesterly winds for Thursday before turning more easterly by Friday. However, such winds will largely be dependent on the position of the front and other convective processes. && .MARINE... Light south to southeast winds are expected through Tuesday, gradually becoming more southwest by Wednesday. A pop up shower or thunderstorm along the bay breeze is possible Tuesday afternoon, with higher chances Wednesday afternoon. Some marginal southerly channeling may approach SCA levels Tuesday evening, but otherwise sub-SCA conditions are most likely. While background wind fields should mainly keep gusts around 10 knots or less on Thursday and Friday, the risk of afternoon/evening convection may bring hazardous conditions to the waters. Initial winds will be out of the northwest before turning more light and variable into Friday. && .TIDES/COASTAL FLOODING... Elevated tidal anomalies look to continue through Tuesday given the recent full moon and light onshore flow. Near minor tidal flooding is possible with high astronomical tides (especially at Annapolis and perhaps Dahlgren/Alexandria). && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...DHOF/EST NEAR TERM...BRO/DHOF SHORT TERM...DHOF LONG TERM...BRO AVIATION...BRO/DHOF MARINE...BRO/DHOF TIDES/COASTAL FLOODING...LWX