Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
820 FXUS61 KLWX 091424 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 1024 AM EDT Sun Aug 9 2026 .WHAT HAS CHANGED... A brief reprieve from t-storms today and turning hotter. T-storm chances return for the new workweek along with the threat for severe weather. && .KEY MESSAGES... - 1) Even less t-storms today with increasing chances for the new workweek. Turning hotter as well with high humidity continuing. - 2) Shower and t-storm chances remain through at least Saturday ahead of a cold front that will bring needed relief to the area. && .DISCUSSION... KEY MESSAGE 1... Even less t-storms today with increasing chances for the new workweek. Turning hotter with high humidity continuing. Shortwave ridging building today as seen on water vapor channels should inhibit thunderstorm for much of the area today. SPC DY1 outlook has cleared the northern half of the CWA from general thunderstorms. Also, smoke is present over the area as seen on GeoColor imagery. As for Monday, the chances for thunderstorms have increased given another piece of shortwave energy ejecting across the region. Current 00z guidance suggests scattered to numerous thunderstorms across the region with a focus east of the Alleghenies Monday afternoon and evening. SPC currently has most of the region in a Marginal Risk (Level 1 out of 5) for severe weather with a Slight Risk (Level 2 out of 5) grazing northwest Garrett Co. MD. Machine guidance is also high on the severe threat with WxNext2 probabilities of 30-60 percent and CSU probabilities of 15 to 30 percent across the area during the Monday into Tuesday timeframe. Even with that said, coverage and timing remain the two big question marks similar to what we saw on Saturday across the region. With a hot and humid airmass in place and marginal shear this will be something to watch in the near term period. Additional shortwave disturbances look to pass through Tuesday into Wednesday and again Wednesday into Thursday. Uncertainty remains in regards to timing and coverage which will dictate the risk for severe weather. Current machine learning guidance and day 4-8 outlooks from SPC mention at least a chance for severe weather each day mainly during the afternoon and evening hours. Ensemble and deterministic guidance put us in an MCS setup which will make it even harder to time out severe weather, especially with complexes of storms moving around the top of the ridge. Once again something that will continue to monitor in the coming days ahead. Outside of he storm chances expect highs in the upper 80s and low 90s with heat indices east of the Blue Ridge up around 100 degrees. The hottest days look to be today and Monday given the strengthened subtropical ridge nearby. Highs will push into the mid 90s with heat indices closer to 105 degrees east of the Blue Ridge/along the urban corridor Monday afternoon. KEY MESSAGE 2...A cold front could arrive late next week bringing relief from the heat and humidity into the upcoming weekend. Daily storm chances look to continue through at least Saturday as a more potent frontal system tracks toward the region. Ahead of that front will be several fast moving shortwave disturbances which will help aid in shower and thunderstorm development during the diurnal period. Storm coverage is a bit uncertain Thursday into late week as the front tries to push through. Speaking of the front, details still remain muddled on it`s passage. Most 00z ensemble guidance suggests a frontal passage late Thursday into Friday while others have a front Friday into Saturday. Other deterministic members try to stall the front to the south Friday into Saturday while bringing it back north through the end of the weekend into early next week. With that said, there is even more uncertainty in regards to severe weather Thursday through Saturday based upon cloud cover and the placement of the front. Of course any decent frontal passage we`ll have to be monitor given machine probabilities remaining between 5- 15 percent for severe weather. Temperatures will cool from the 90s into the low to mid 80s late week. Overnight lows will fall back into the low to mid 60s with 50s over the mountains. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... Prevailing VFR conditions are expected across the terminals through at least Thursday given subtropical high pressure offshore and the lack of any real front passing through. Brief periods of sub-VFR are likely during the afternoon and evening hours due to thunderstorms. Today will bring the least amount of t-storms between the terminals given a strengthened subtropical ridge over the region. An isolated shower or t-storm could pop up this afternoon west of MRB and south of CHO/SHD between 18z-00z/2-7pm. Coverage will be very isolated in nature with most seeing nothing at all. Winds will remain light out of the west and southwest at less than 15 kts. Storm coverage increases Monday into Tuesday as another shortwave disturbance passes through. The risk for severe weather is also increasing during this time with a focus during the peak heating period 18z-01z/2-8pm Monday afternoon and evening. Storm coverage remains uncertain with gusty winds, frequent lightning, and locally heavy rainfall as the primary concerns. Similar conditions are expected Tuesday and Wednesday with restrictions possible in the afternoon and evening due to thunderstorms. Outside of the thunderstorms expect patchy fog between the terminals each morning through Friday. Winds will remain light out of the west and southwest at less than 15 kts. Temporary restrictions will continue at times due to showers and thunderstorms through at least Saturday as we await a cold front to sweep through. && .MARINE... Sub-SCA level winds are expected today with occasional gusts up to 15 kts over the open waters of the Chesapeake and tidal Potomac. A brief period of southerly channeling may return to the open waters Monday afternoon and evening. Overall sub-SCA level winds are expected through Thursday morning. Outside of the background winds, expect daily shower and thunderstorm chances are each afternoon and evening through upcoming workweek. The least amount of coverage will be today with greater coverage Monday and Tuesday afternoon/evening. Special Marine Warnings may be needed to encompass any stronger thunderstorms that may form. Damaging wind gusts and frequent cloud-to-ground lightning will be the main threats between 19z-01z/ 3-9pm. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ DISCUSSION...LFR/JMG/EST AVIATION...LFR/JMG/EST MARINE...LFR/JMG/EST