Area Forecast Discussion
Issued by NWS Sterling, VA

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146 FXUS61 KLWX 290154 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 854 PM EST Mon Nov 28 2016 .SYNOPSIS... A warm front will lift north through the area Tuesday. An area of low pressure will move across the area Wednesday with a cold frontal passage Wednesday night. High pressure will return to the region during the weekend. && .NEAR TERM /THROUGH TUESDAY/... Weak radar echoes have been cross the Potomac Highlands on KLWX this evening. No rainfall has been reported yet. A warm front across northern GA/SC will continue to move northward this evening. Temperatures have been dropping however as clouds...showers and the warm front move northward temperatures will begin to rise after midnight. A 50-kt jet at 850mb will move into the Mid- Atlantic tonight and continue through Tuesday morning. A wind advisory was issued for elevations above 2000 feet. Lower elevations will be in a stable enviornment with little mixing through early Tuesday but southerly winds will increase during the day Tuesday with potential gusts near 30 mph as mixing increases across the area. Showers will move into the region overnight and through Tuesday morning. Due to the strong windfield...showers will move quickly across the region and rainfall amounts will be around 0.25-0.5 inches across the region. Dry air moves into the mid-levels by Tuesday afternoon and showers should move out of the region. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... Shortwave- ridge aloft and associated subsidence should be conducive to widespread low clouds and fog Tue night. MOS guidance is showing strong signal for development of dense fog. On Wed, upper low over the upper midwest moves across the western Great Lks. Models indicate significant height falls in the order of 200 meters will occur over the area between 12Z Wed and 12Z Thu promoting large scale forcing for upward vertical motion. A new sfc low develops over the OH valley Wed with showers and perhaps a few thunderstorms developing over the area Wed and continuing into Wed evening along/ahead of a cdfnt. There could be strong gusty winds Wed afternoon and evening given strong environmental flow and marginal instability (200-400 J/kg of CAPE). Another quarter to half inch of rain is expected. Frontal zone clears the area by 06Z Thu with showers ending. && .LONG TERM /THURSDAY THROUGH MONDAY/... High pressure builds in behind cold front on Monday and remains into Sunday... therefore another period of dry conditions is expected Thursday into Sunday. Sunday into Monday guidance is in disagreement... GFS shows an upper level shortwave trough late on Sunday into Monday... while the Euro shows a warm front lifting from the Gulf states. Either scenario, there will be an increase in chance of precipitation sometime on Sunday and into Monday. Temperatures will be near or slightly above normal, with high temperatures in the 40s and 50s, and low temperatures mainly in the 30s, and some 40s... higher elevations could see some 20s. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... Showers moving in late tonight with low-level wind shear and developing MVFR conditions. Mixing will occur Tuesday and S winds 10-15 kts with gusts around 20-25kts expected mainly at IAD/DCA/BWI/MTN. There is a potential for higher gusts but confidence is low at this time. IFR conditions are also possible Tuesday mainly in the morning but strong wind field may keep ceilings MVFR. Widespread LIFR/VLIFR conditions Tue night under shortwave-ridge aloft and weak pressure gradient. Another round of showers Wed with gusty winds and MVFR/IFR conditions. Cdfnt pushes through the area Wed night with drying conditions and shifting winds. Dry conditions expected for Thursday into Saturday with high pressure dominating weather conditions. So, mainly VFR conditions expected. && .MARINE... Solid SCA conditions expected tonight and especially Tue. Strong winds aloft will move across the waters Tuesday and Gale force winds are expected on the lower tidal potomac and Cheapeake Bay south of Sandy Pt. The potential for gale force winds exists further north on the bay but confidence is low. Dry conditions expected for Thursday into Saturday with high pressure dominating weather conditions. So, mainly VFR conditions expected. Gusty winds possible Friday into Friday night, so small craft advisory may be needed. && .TIDES/COASTAL FLOODING... Elevated water levels are expected Tue and Wed due to strong srly flow. At this time, minor flooding is possible, but this will need to be monitored closely. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Wind Advisory until 1 PM EST Tuesday for MDZ501. VA...Wind Advisory until 1 PM EST Tuesday for VAZ025>027-029-503- 504-507-508. WV...Wind Advisory until 1 PM EST Tuesday for WVZ055-501>503-505- 506. MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ532>534-537- 540>543. Small Craft Advisory from 6 PM Tuesday to 6 AM EST Wednesday for ANZ532>534-537-540>543. Gale Warning from 6 AM to 6 PM EST Tuesday for ANZ532>534-537- 540>543. Small Craft Advisory until 6 AM EST Wednesday for ANZ531-536- 538-539. Small Craft Advisory from 3 AM to 6 PM EST Tuesday for ANZ530- 535. && $$ SYNOPSIS...LFR NEAR TERM...HSK/LFR SHORT TERM...LFR LONG TERM...IMR AVIATION...HSK/IMR/LFR MARINE...HSK/IMR/LFR TIDES/COASTAL FLOODING...HSK

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