Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 220221 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 921 PM EST Wed Feb 21 2018 .SYNOPSIS... A cold front will pass through this evening before stalling out to our south Thursday. The boundary may return north as a warm front Saturday before a stronger cold front passes through from the west on Sunday. High pressure will return for early next week. && .NEAR TERM /THROUGH THURSDAY/... Cdfnt is currently moving across the area this evening and extends from BWI swwd through near Dulles and New Market, VA. Temps and dewpoints are in the 70s/60s respectively south of the front and mid 60s/mid 50s north of the front under a northerly wind. Only a few showers are expected along the front this evening as it continues to push south of the area. By 06Z, front should have cleared the entire fcst area except perhaps Nelson county where it will get hung up. Really, not a lot of shower activity expected until very late tonight (after ~09Z or so) when some shortwave energy will approach the Appalachians. By this time tomorrow, temperatures will be more than 30 degrees colder than at present, with some places perhaps nearly 40 degrees lower. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... Wave of low pressure passes northeast along the stalled front on Thursday night, with rain diminishing, but drizzle will linger. We still have a small threat of freezing rain later at night across northern portions of the region, particularly western Maryland, depending on how much cold air can build south across the region. Another wave of low pressure will develop in Texas and move northeast along the front early Friday, with another round of rain expected in the morning. By afternoon, this wave should be north of the region, and it will just be cloudy and drizzly again. Temperatures should warm a bit, perhaps reaching the low 50s late. Warm front aloft pushes north Friday night, but the surface front will be stuck to our south thanks to the high to the northeast providing a low level cold air wedge, so it will remain relatively cool and drizzly. However, temperatures should be steady or slowly rising as the cold air gradually erodes. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A frontal boundary will be stalled over our area on Saturday separating a colder air mass from warm air. The boundary will lift as a warm front Saturday night while a cold front moves through on Sunday. These will allow for rain showers over our area from Saturday into Sunday. Conditions should be drying out Sunday night and remain dry through Wednesday as high pressure builds in from the west and then settles overhead. Temperatures will be above normal Saturday and Sunday and then gradually become more normal by mid-week. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... As a cold front continues to cross the region this evening, a few showers will be possible. Winds will turn northerly behind the front, and low ceilings with MVFR conditions are forecast develop by early Thursday morning. MVFR/IFR conditions are then likely in low clouds, areas of rain, and drizzle Thursday, Thursday night, and potentially lasting into Friday. Sub-VFR conditions possible Saturday into Sunday with a frontal boundary affecting our area. VFR conditions should return on Monday with high pressure building over us. && .MARINE... With warm air temperatures expected over considerably cooler waters, the strongest gusts will likely be observed along the shorelines. As a cold front crosses the region tonight, winds will turn northerly behind the front, and now look more likely to reach SCA criteria, so have raised one for the bay and adjacent waters (except the Potomac) for after midnight. Northeast flow looks to remain elevated on Thursday, so maintain SCA thru the day. It may need additional extension into the evening, but at this point am not confident about this so have cut it off at the end of the day. As the front starts a gradual retreat back to the north on Friday, winds should diminish below SCA. Winds are expected to remain below SCA criteria on Saturday. Sunday winds will increase and come close to criteria, so it should be monitored in case a SCA is needed. Winds will decrease on Sunday night and remain below criteria into Monday. && .CLIMATE... The all-time February highest minimums are: 61 at DCA/Washington (2/17/1891) 58 at BWI/Baltimore (2/17/1891) 55 at IAD/Dulles (2/17/1976) - records only go back to 1960 at IAD The all-time February highest maximums are: 84 at DCA/Washington (2/25/1930) 83 at BWI/Baltimore (2/25/1930) 79 at IAD/Dulles (2/24/1985 and 2/25/2000) - records only go back to 1960 at IAD Record warm daily maximum temperatures Wed 2/21 DCA 75 (1953) BWI 74 (1930) IAD 70 (1997) Record warm daily minimum temperatures Wed 2/21 DCA 51 (1954) BWI 49 (1981) IAD 45 (1981) && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 6 PM EST Thursday for ANZ530>534- 537>543. && $$ SYNOPSIS...RCM NEAR TERM...LFR SHORT TERM...RCM LONG TERM...IMR AVIATION...IMR/RCM MARINE...IMR/RCM CLIMATE...LWX

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