Area Forecast Discussion
Issued by NWS Sterling, VA

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774 FXUS61 KLWX 111433 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1033 AM EDT Sun Apr 11 2021 .SYNOPSIS... A cold front is expected to cross the region early this evening. Showers and a couple of thunderstorms ahead of and along the front will clear the region late this evening. Dry conditions expected Monday before a secondary front swings across the region late Monday into early Tuesday. High pressure will briefly return late Tuesday into Wednesday. However; the next low pressure system may impact the region towards the latter portion of the week. && .NEAR TERM /THROUGH TONIGHT/... Light showers and patches of drizzle will rotate around a weak low over northeast Maryland as they move toward the northeast over the next few hours. Aside from isolated showers over western Maryland and some cloud cover in the mountains, most of the region will have plenty of sunshine through early to mid afternoon. As a cold front approaches our CWA later this afternoon and early this evening, showers and a couple of strong thunderstorms should erupt and move from southwest to northeast. The first couple of showers and storms could develop along the Central Blue Ridge Mountains and part of the Potomac Highlands around 2pm or 3pm. Additional showers and thunderstorms would develop and be scattered in coverage closer to 4pm. The eastern half of our CWA is in a Marginal Risk for Severe Thunderstorms this afternoon and evening. This would be an area from Frederick, Maryland to Leesburg to Orange in central Virginia and all areas to the Chesapeake Bay. The main threats with the thunderstorms would be damaging wind gusts and large hail. Temperatures have reached the upper 60s to lower 70s where there has been mostly sunny skies during the morning. Expect these temperatures to climb a couple more degrees into mid afternoon before convection slows this ascent. Cooler temperatures in the mountains. Any shower and thunderstorm activity is expected to end from west to east later this evening as a dry slot works its way over the region. Temperatures will drop into the upper 40s to the middle 50s across the region as this dry air works its way into the region. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The main cold core low pressure system over central Indiana that will be responsible for sending waves of energy in our direction will move closer to our region on Monday. The cold core aloft interacting with slightly warmer temperatures in the lower levels will combine with energy to produce periodic shower activity and perhaps a clap of thunder in places Monday afternoon and evening and again on Tuesday afternoon. Weak high pressure will build back into the region late Tuesday into Wednesday. However another area of low pressure may impact the region towards the latter portion of the week. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Very unsettled and cool wx pattern is expected to develop during the middle portion of the week as a deep closed upper low drops from the western Great Lks to the northern Mid-Atlantic. Overall, guidance have trended much more amplified, and thus, slower with upper level pattern mid week. A well organized sfc low now develops on the DE/srn NJ coast Thu in response to deepening trof/closed low upstream leading to better chance for rainfall and cooler wx. Even some wet snow is possible for the Appalachian region Thu-Thu night. Weather begins to gradually improve and turn a little warmer toward the end of the week && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... A few stratus fractus clouds streaming by late this morning; otherwise, VFR conditions through this afternoon. A cold front approaching could ignite showers and a couple of strong to severe thunderstorms this afternoon into early this evening, resulting in lower CIG/VSBYs. Mainly VFR conditions are expected for the beginning of the week. However sub-VFR conditions may arise periodically over BWI and MTN in instances of light, periodic showers. Unsettled wx is expected during the middle portion of the wx with numerous showers, extensive cloud cover, and periods of MVFR cigs. && .MARINE... A SCA for the lower Tidal Potomac and lower Bay remains in effect through 6PM this evening. A recent SCA issued for upper Potomac and remainder of the Bay until Noon. Showers and thunderstorms associated with the aforementioned cold front may require the issuance of Special Marine Warnings this afternoon and evening, with the primary threat being gusty winds and hail. High pressure returns later tonight through Monday night, with a weak gradient and sub SCA conditions expected. Another cold front will cross the area early Tuesday, with sub SCA conditions persisting. Northwest to north winds will continue Wednesday and Thursday as high pressure builds well to our northwest, however winds look to mainly stay below Advisory thresholds. SCA conditions are likely for the second half of the week in WNW to NW flow. && .TIDES/COASTAL FLOODING... A light southerly breeze will continue to yield elevated water levels through this afternoon. The sensitive sites could still encounter near threahold over the next several high tide cycles. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until noon EDT today for ANZ531>533-535- 538>541. Small Craft Advisory until 6 PM EDT this evening for ANZ534- 537-543. && $$ SYNOPSIS...MSS NEAR TERM...MSS/KLW SHORT TERM...MSS LONG TERM...LFR AVIATION...LFR/KLW MARINE...LFR/KLW TIDES/COASTAL FLOODING...KLW

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