Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
435 FXUS61 KLWX 121930 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 330 PM EDT Wed Aug 12 2026 .WHAT HAS CHANGED... Have raised chances for showers this evening as a decaying line potentially tracks across the area. However, confidence does remain on the lower side given all of the thick high clouds overhead. Otherwise, the forecast largely remains on track. && .KEY MESSAGES... - 1) Decreasing storm coverage today before ramping up late in the week with a returning warm front. - 2) Showers and thunderstorms possible between Sunday and Monday before becoming drier into early next week. && .DISCUSSION... KEY MESSAGE 1...Decreasing storm coverage today before ramping up late in the week with a returning warm front. The earlier frontal boundary has now settled down near the Virginia-North Carolina border. To the north, temperatures are holding steady in the low/mid 80s with mainly 60s dew points. With diurnal heating, some shallow cumulus fields have formed, but these are largely capped by the limited instability. Otherwise, filtered sunshine is noted amidst passing high clouds and elevated smoke from the western U.S. wildfires. Upstream convection which continues to train over eastern Indiana/western Ohio should stay well west of the local area. Convective activity is likely to follow the instability gradient which ushers this convection into eastern Kentucky. Aside from this complex, a few high-resolution solutions attempt to form some cells across the Lower Great Lakes. This would carry isolated showers and embedded thunderstorms toward the Mason- Dixon Line by the mid/late evening. While not severe, these could carry a risk of brief heavy rainfall and lightning. Any such activity exits toward the Eastern Shore after around 2 AM. Some patchy fog may form west of the Blue Ridge, accompanied by area-wide lows in the 60s, with low 70s along/east of I-95. Heights further build on Thursday into Friday as upper ridging stretches up from the Gulf of America into the central and southeastern U.S. Locally, being north of this ridge will favor continued northwesterly flow aloft which carries the risk of mesoscale convective systems (MCS) intrusions. On Thursday, the main shower and thunderstorm chances focus across the Alleghenies down into the central Virginia Piedmont and I-64 corridor. This largely ties to the front still being displaced off toward the south. Eventual northward progression is possible into Friday which introduces a better chance for storms. The latest ensembles support probabilities in the 40 to 70 percent range. While not a washout by any means, this should be heavily guided by the peak in daytime heating. High temperatures each day will be in the 80s to low 90s, with 70s for the mountains. Likewise, seasonable conditions can be expected overnight. Ample high pressure builds to the north of the region on Saturday as the frontal zone again sags back toward the Carolinas. An onshore component to the wind could keep some additional cloud cover around. However, overall trends suggest a drop off in humidity before winds return to southerly late in the weekend. KEY MESSAGE 2... Showers and thunderstorms possible between Sunday and Monday before becoming drier into early next week. Upper-level ridging continues to build over the Southwest CONUS over the weekend, with multiple shortwave troughs tracking to the east offshore of New England. Beginning Sunday, an upper-level perturbation forms over the Canadian Rockies and tracks eastward, with a stemming frontal boundary tracking across the East Coast late Sunday and into Monday. This boundary will likely bring chances for scattered showers and thunderstorms here in the Mid-Atlantic, although model guidance has been somewhat marginal on the severe potential for this event. As of the 12z ensemble runs, several outputs have the highest likelihood for severe weather just south of the area towards southern VA and the Carolinas, while the GFS ensemble runs still have a 15%-30% probability for severe weather centered within the region. Should any thunderstorms become severe, the most likely hazards will likely be elevated wind gusts as well as locally heavy rainfall. As drought conditions continue to improve within the region, flooding potential becomes more of a concern with any heavy rainfall-producing thunderstorms that materialize. Otherwise, temperatures remain near-normal for mid-August, with humid conditions as well as temperatures ranging in the 80s and lower-90s at times near the metros. High pressure moves into the region once the frontal boundary passes offshore by Tuesday, bringing drier conditions to the region. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... While VFR conditions are expected into Thursday, have introduced a PROB30 for thunderstorm restrictions late this evening. Otherwise, winds remain somewhat variable and light given continued weak gradients. Winds on Thursday should be mainly out of the west to northwest with the frontal zone off to the south. Any afternoon/evening storms should be confined closer to I-64 around KCHO, with others to the north remaining dry. More widespread showers and thunderstorms are possible on Friday which would favor further convective-driven restrictions. High pressure builds to the north on Saturday which should favor VFR conditions amidst east to northeasterly winds. Beginning Sunday, a cold front could bring sub-VFR conditions to terminals as scattered showers and thunderstorms are possible throughout the region. These conditions could be intermittent through Monday as the front passes through. Southeast winds shift northwest Monday evening in the wake of the front. && .MARINE... Background winds remain on the weaker side as a frontal zone sags off toward the south. Gusts will mostly be in the 5 to 10 knot range, while pushing up to 15 knots at times when southerly channeling occurs. The main threat for hazardous marine conditions would be on Friday given more widespread showers and thunderstorms. Any storm will be capable of gusty winds and frequent lightning. This front drops toward the Carolinas on Saturday as high pressure builds over the northeastern U.S. The resulting winds will mainly be out of the east to northeast. SCAs will likely be needed by Sunday afternoon as a cold front tracks through the region. Between Sunday & Monday, gusty showers and thunderstorms are possible over the waters. Winds diminish once the front passes through late Monday. Southeast winds shift northwest by Monday evening in the wake of the front. && .TIDES/COASTAL FLOODING... Water levels will slowly elevate in the next couple of days. This brings a more sensitive location like Annapolis into Action Stage for the Thursday morning high tide. However, there is currently no discernible threat for coastal flooding this week. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ DISCUSSION...BRO/SRT AVIATION...BRO/SRT MARINE...BRO/SRT TIDES/COASTAL FLOODING...BRO