Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 261454 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 954 AM EST Sun Feb 26 2017 .SYNOPSIS... High pressure will return to the area today and Monday. A warm front will then lift north into the area Tuesday into Wednesday followed by another cold front Wednesday night. && .NEAR TERM /THROUGH TONIGHT/...
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Going forecast in very good shape, and relatively few adjustments were needed. High pressure centered over Tennessee has begun to push into the western edge of the forecast area. Winds are still gusty in the cold advection on the northern side of this ridge. Further, satellite images depict a shield of stratocumulus in the cyclonic flow. Each of these will gradually dissipate through the afternoon as the ridge builds. High temperature forecasts are well supported by recent LAMP runs...mid 40s to lower 50s. Tonight will be tranquil as the high moves off the Outer Banks. Some mid level clouds will advance late, but there should still be some radiational component to temperatures. 20s will be possible in outlying areas, with lower to mid 30s elsewhere.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... The pattern becomes a bit more ambiguous (in terms of well- defined features) for Monday and Tuesday. The surface high will set up offshore, with the subtropical ridge aloft surging a bit, placing the Mid-Atlantic in fast WSW flow. We can say with some certainty that there will be more clouds than sun, and temperatures will rise back above normal. Any precipitation will be more difficult to time, driven by packets of isentropic ascent and subtle shortwave troughs. Monday is looking like the drier day, with only a small chance of showers across the northern quarter of the area in the afternoon. The better chance of rain will come sometime on Tuesday as a warm front lifts into the area, but due to timing difference, have kept POPs in the chance category. Tuesday may also be a bit breezy if low level jet winds can mix to the surface. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Wedge may linger early Wednesday but guidance is unanimous in pushing warm front north and bringing warm sector into region with 70s and a breezy S wind likely. Showers and perhaps a few more thunderstorms possible especially as cold front approaches late and at night. May have concerns as we did today, timing may affect any severe threat though. Gusty NW wind and much cooler behind the front on Thursday. Upslope snow showers possible along Allegheny Front, otherwise dry. A weak clipper system then swings through on Friday, with a reinforcing shot of cold air behind it. Right now odds favor rain versus snow with this system as the low stays a bit too far north, but something to watch. Saturday then turns into a cold, blustery day with highs struggling to reach the 40s in many areas. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... NW flow continues today, with 20-25 kt gusts possible through midday before subsiding this afternoon. Stratocu will be broken around FL050 at times through early afternoon as well. No issues are expected tonight as high pressure slips south of the area, which will continue through Monday as winds become southerly around 10 kt. Conditions may deteriorate to at least MVFR heading into Tuesday and Tuesday night as a warm front lifts into the area -- both in terms of low clouds and period(s) of rain showers. Sub-VFR cigs and vis possible Wednesday and Wednesday night as warm front lifts north of the area followed by a cold front. There is a slight chance of thunderstorms with the cold front. Gusty NW winds (30 knots likely) with VFR cigs/vis on Thursday. && .MARINE...
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Winds on the lower edge of Small Craft Advisory criteria in northwest flow this morning. Model sounding continue to suggest 20-25 kt gusts through midday, before gradually subsiding this afternoon. High pressure will be building fromt he southwest, suggesting that portions along the Potomac will be the first places to relax. Will leave SCA expiration at 4 PM for now, but some portions of the waters likely will be able to be cancelled before that. High pressure will move south of the area tonight, with lighter winds becoming southerly by Monday morning. Southerly flow will be the rule through Tuesday night. Wind fields are still relatively light on Monday, right near the cusp of SCA criteria. Have favored a forecast just below for now, but the threat will need to be reexamined for Monday afternoon. SCA conditions look more likely on Tuesday with a low level jet over the region. SCA looks likely on southerly winds as warm front lifts north of the region Wednesday, then gales possible Wednesday night and Thursday behind the cold front. A slight chance of thunderstorms also exists late Wednesday and Wednesday night as the cold front comes through.
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&& .CLIMATE... Warmest Februaries (average temperature) DCA BWI IAD 1. 46.9 (1976) 44.0 (1976) 42.1 (1990) 2. 45.2 (1990) 43.9 (1949) 41.1 (1976) 3. 44.7 (1997) 43.3 (1890) 41.0 (1998) 4. 44.3 (2012) 42.7 (1932) 40.9 (2012) 5. 43.9 (1949) 42.6 (1909) 40.5 (1997) Feb 2017 (through the 25th) DCA: 47.6 BWI: 44.3 IAD: 45.1 Warmest Winters (Dec 1-Feb 28/29) DCA BWI IAD 1. 44.7 (1931-32) 45.3 (1931-32) 40.0 (2011-12) 2. 44.3 (1889-90) 44.4 (1889-90) 39.7 (2001-02) 3. 43.3 (2011-12) 42.4 (1948-49) 39.4 (1997-98) 4. 43.2 (2001-02) 41.9 (1949-50) 39.0 (2015-16) 5. 42.8 (1949-50) 41.3 (1879-80) 38.3 (1990-91) Winter 2016-17 (through Feb 25) DCA: 43.8 BWI: 40.5 IAD: 40.9 Driest Februaries (total precipitation) DCA BWI IAD 1. 0.35 (2009) 0.26 (2009) 0.25 (1978) 2. 0.42 (1978) 0.36 (2002) 0.35 (2009) 3. 0.47 (2002) 0.56 (1978) 0.46 (2002) 4. 0.62 (1901) 0.63 (1977) 0.49 (1977) 5. 0.66 (1977) 0.65 (1901) 0.68 (1968) Feb 2017 (through the 25th) DCA: 0.34 BWI: 1.21 IAD: 0.33 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 4 PM EST this afternoon for ANZ530>543. && $$ SYNOPSIS...RCM NEAR TERM...HTS/ADS SHORT TERM...ADS LONG TERM...RCM AVIATION...ADS/RCM MARINE...HTS/ADS/RCM CLIMATE... is the U.S. government's official web portal to all federal, state and local government web resources and services.