Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 201854 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 254 PM EDT Tue Jun 20 2017 .SYNOPSIS... High pressure will be perched west of the area through Thursday. A cold front will cross the area Friday into Saturday, with tropical moisture streaming north ahead of it. && .NEAR TERM /THROUGH TONIGHT/... Drier air slowly infiltrating the forecast area. Broad, diffuse high pressure west of the area this afternoon, and will remain west of the area through the night. Dewpoints now in the 50s areawide, which should make for a comfortable evening. Some mid level clouds likely will preclude optimal cooling; thus low temperature forecasts for tonight will be higher than dewpoints. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... Weather will be benign for the next couple of days. A shortwave crossing from the Great Lakes to the northeast Wednesday could provide a little moisture. Have limited chance PoPs (mostly showers, perhaps a rumble of thunder) to northern Maryland and the Potomac Highlands. The lingering baroclinic zone from yesterdays cold front could also yield a thunderstorm to the tip of southern Maryland. Thursday we will be in the subsidence in the wake of the trough axis. Temperatures at 850 mb do rise slightly, so will bump high temps up to near 90. Dewpoints increase a pinch as well, into the 60s. Eyes will then turn to the Gulf of Mexico to see what the pace of that precip will be. Given the range of possibilities will take a tempered approach...20-30 PoP after midnight. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Moisture and perhaps circulation from the remnants of Tropical Storm Cindy look to be drawn toward the Mid-Atlantic ahead of a cold front that is expected to cross the area Friday night into Saturday. This could produce enhanced rainfall Friday until the cold frontal passage over the Mid-Atlantic. Once the cold front passes, 12Z GFS/ECMWF suggest weak surface high pressure over the area for the rest of the outlook period. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... VFR conditions for the valid TAF period and beyond. Winds west or southwest at 10 kt or less through Wednesday. There could be a few sprinkles or a light shower Wednesday afternoon, especially MRB. Do not believe that there will be an operational impact. Flow turns more southerly Thursday; again, no impacts. Remnants from Cindy look to be drawn to the Mid-Atlantic Friday into Saturday ahead of a cold front that crosses on Saturday. This may lead to enhanced rainfall and limited aviation conditions. && .MARINE... Am holding onto the Small Craft Advisory for this afternoon at this time. While it`s not verifying thus far, model momentum transfer equations suggest that the period of best opportunity (albeit brief) will be late afternoon. These winds may linger tonight for the Drum Point to Smith Point/Tangier Sound area, where the pressure gradient would be greater. Winds will be southerly, or have a primary south component, through Thursday. From this vantage point, it appears as though gusts shouldn`t exceed 10-15 kt. Remnants from Cindy look to be drawn to the Mid-Atlantic Friday into Saturday ahead of a cold front that crosses on Saturday. This may lead to enhanced rainfall and SCA level winds over the Chesapeake Bay. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ530>533-538>542. Small Craft Advisory until 6 AM EDT Wednesday for ANZ534-537- 543. Small Craft Advisory until 6 PM EDT this evening for ANZ535- 536. && $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS LONG TERM...BAJ AVIATION...HTS/BAJ MARINE...HTS/BAJ

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