Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 081853 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 253 PM EDT Sat Aug 8 2020 .SYNOPSIS... High pressure will build across the region over the next few days. A cold front will approach from the northwest next week, stalling in the area as the week progresses. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Isolated showers are develop along the southern Blue Ridge Mountain near the stalled front. Additional showers and perhaps a thunderstorm could develop over central Virginia late this afternoon with additional daytime heating and instability. There is a Marginal Risk for flooding rainfall from these showers and thunderstorms due to the slow movement. High temperatures were knocked down a couple of degrees as morning and midday cloud cover played a big role in the lack of expected warmth. High pressure will build into our region tonight. A few showers could linger over our southeastern zones but should diminish overnight. Low temperatures for tonight will be in the 60s and low 70s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... High pressure will build overhead Sunday as the pattern remains a zonal flow aloft. Conditions should remain dry in most areas on Sunday, with maybe an isolated shower developing due to terrain circulation over central Virginia. Dry conditions will remain into Sunday night. High temperatures will be in the upper 80s and low 90s, with the highest heat index values reaching into the mid 90s. Weak high pressure will remain in control on Monday but a shortwave trough aloft and southerly flow advecting moisture into our region, could allow for the development of a few isolated showers and thunderstorms. Heat index values could reach the upper 90s over most areas across our CWA. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure will remain over the Atlantic Ocean for Tuesday and Wednesday, and a light southerly flow will allow for more hot and humid conditions. The heat and humidity will likely lead to isolated/scattered showers and thunderstorms each day, especially during the afternoon and evening hours. A cutoff low may develop to our west for Thursday through Sunday while high pressure builds over New England, sending a backdoor boundary toward the area. The exact details are uncertain this far out, but with a boundary nearby combined with a possible easterly component from the Atlantic along with more humid conditions. This will provide a setup for unsettled conditions with showers and thunderstorms possibly being more widespread. Locally heavy rainfall is possible during this time. Again, confidence remains low this far out. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... MVFR cigs remain near IAD for low clouds and CHO terminal for low clouds and developing showers, while VFR conditions exist at other terminals. VFR conditions at all terminals this evening will shift to an MVFR low clouds and low visibility set up due to low clouds and patchy fog again tonight and then again Sunday night. Patchy low clouds and fog are possible during the overnight and early morning hours each day Tuesday through Thursday due to plenty of moisture in place, and the possibility of it getting trapped underneath the nocturnal inversion. A few afternoon and evening showers and thunderstorms are possible each day. Coverage may be more widespread Thursday as a boundary interacts with the area. && .MARINE... Winds are expected to remain below Small Craft Advisory criteria into Monday night. Some convection could bring gusty winds this afternoon over the southern portion of the Bay, and lower Tidal Potomac. This should improve tonight. There will be less chance for any convection Sunday into Sunday night, a slight chance for Monday afternoon/evening. High pressure will remain over the Atlantic Tuesday through Thursday, providing a southerly flow. Winds should remain below SCA criteria for most of the time since the flow will be light. A few afternoon/evening showers and thunderstorms are possible Tuesday and Wednesday. There is a chance that convection may be more widespread Thursday afternoon/evening as a boundary from the north and east approaches. && .TIDES/COASTAL FLOODING... Elevated water levels will persist over the next few days. The flow will be light, so the most likely scenario is that sensitive areas will be around action stage. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...KLW NEAR TERM...KLW SHORT TERM...KLW LONG TERM...BJL AVIATION...BJL/KLW MARINE...BJL/KLW TIDES/COASTAL FLOODING...BJL is the U.S. government's official web portal to all federal, state and local government web resources and services.