![National Oceanic and Atmospheric Administration](/build/images/header/noaa.d87e0251.png)
![National Weather Service](/build/images/header/nws.4e6585d8.png)
![United States Department of Commerce](/build/images/header/doc.b38ba91a.png)
Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
940 FXUS61 KLWX 170756 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 356 AM EDT Sat Aug 17 2024 .SYNOPSIS... An approaching cold front will bring daily shower and thunderstorm chances this weekend and into early next week. Dry conditions and cooler temperatures return Tuesday as high pressure builds in from the northwest. && .NEAR TERM /THROUGH TONIGHT/... An approaching cold front will bring widespread shower and thunderstorm chances to the forecast area this afternoon. As of 3:45 AM, a line of rain showers is moving northeast along the I-95 corridor. Cloud cover lingering from early morning precipitation could hinder afternoon shower and thunderstorm chances. Modest CAPE values of 1000 to 2000 J/kg could lead to some storms being strong if convection initiates during peak daytime heating. The primary hazard for today will be heavy rainfall with isolated instances of flooding. PWAT values approaching and exceeding 2 inches are expected this afternoon. The most vulnerable areas will be those in NE Maryland and in metro areas that are sensitive to urban flooding. Along with heavy rainfall, damaging wind gusts are the primary threats expected with convection this afternoon. High temperatures will be in the 80s for most with some valleys getting into the 90s. Higher elevations will stay in the 70s. Overnight low temperatures will dip into the mid 60s to low 70s areawide. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... Daily shower and thunderstorm chances continue Sunday and into Monday as a cold front approaches and moves through the forecast area. The greatest chance for thunderstorms will be Sunday evening and overnight into Monday as the cold front moves through the area and an upper level trough pivots overhead. Some storms could be strong with CAPE values between 1000-2000 J/kg, lapse rates nearing 6 C/km, and bulk shear nearing 30 knots though parameters remain marginal. Heavy rainfall continues to be an expected threat with PWATS near or exceeding 1.75 inches. Showers and an isolated thunderstorm linger Monday in the wake of the cold front, with conditions less favorable for convection compared to Sunday and Sunday night. Temperatures will be slightly cooler on Monday in the way of the cold front. Highs in the 70s to upper 80s on Sunday will cool to highs in the upper 60s to lower 80s on Monday. Overnight low temperatures will be in the upper 50s to 60s each night. && .LONG TERM /MONDAY THROUGH FRIDAY/... Canadian high pressure will gradually build into the region in the wake of a frontal passage Monday afternoon and settle overhead by next Friday. Temperatures will feel more like late September than late August, some 10 degs below normal. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... Sub-VFR conditions are expected at all terminals this weekend as a cold front approaches and moves through the area. Reduced ceilings are expected, as well as reduced visibilities during precipitation. Daily shower and thunderstorms are expected through Monday with precipitation chances peaking each afternoon. Outside of showers and thunderstorms, expect southerly winds gusting to 15 kts this weekend. Winds shift to westerly and then northwesterly on Monday. Prevailing VFR conditions are expected throughout the long term period with no significant weather in the forecast. && .MARINE... Small Craft Advisory conditions continue today with southerly winds gusting 20 to 25 kts in the Chesapeake Bay. Winds remain SCA criteria overnight will diminishing slightly, gusting 15 to 20 kts out of the south. On Sunday, winds remain out of the south blowing right at or slightly below SCA criteria. Winds shift to westerly Monday morning before shifting to northwesterly in the afternoon. Winds are expected to remain below SCA criteria throughout the day before increasing overnight Monday into Tuesday. SMWs are possible each afternoon with daily shower and thunderstorm chances. SCA conditions are expected Tue into Wed in NW to N flow. && .TIDES/COASTAL FLOODING... Minor coastal flooding will continue at Annapolis through early next week in gusty southerly flow. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Small Craft Advisory until 4 PM EDT this afternoon for MDZ008. Coastal Flood Advisory until 7 AM EDT this morning for MDZ014. VA...None. WV...None. MARINE...Small Craft Advisory until 4 PM EDT this afternoon for ANZ530>534-537>543. && $$ SYNOPSIS...AVS NEAR TERM...AVS SHORT TERM...AVS LONG TERM...LFR AVIATION...AVS MARINE...AVS/LFR TIDES/COASTAL FLOODING...LFR