Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 252023 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 323 PM EST Sat Feb 25 2017 .SYNOPSIS... A cold front will cross the area today. High pressure will return to the area Sunday through early next week. A warm front will then lift north into the area Tuesday into Wednesday followed by another cold front Wednesday night. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Line of strong to severe convection along the I-95 corridor as of 3pm. These storms have become mature enough to dump not just hail but develop rotating updrafts. Severe thunderstorm watch in effect until 8pm. However, HRRR/RAP timing suggests storms will be east of forecast area by 5 or 6pm. We will be dropping the Watch behind the line of convection as appropriate. Temperatures will fall quickly as the front passes, and westerly winds will increase with gusts of 30-40 mph possible. The best surge of winds may come during the early evening. Lows will ultimately bottom out in the 30s, with some 20s west of the Blue Ridge. A period of upslope snow showers could produce localized amounts up to an inch west of the Allegheny Front.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... High pressure moves in from the west Sunday, allowing winds to gradually relax. Highs will be much cooler but closer to normal in the mid 40s to lower 50s. Lows will fall back to the upper 20s and 30s Sunday night as the high begins to move east. While no well defined system is expected for Monday into Monday night, there will be increased isentropic lift, and an inverted trough may develop along the Carolina coast to SE VA. Will have gradually increasing chances of showers through the period, highest S/E of DC Monday night. Temperatures will gradually warm back up as well. && .LONG TERM /TUESDAY THROUGH SATURDAY/...
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A storm system and its associated front will move across the region and to the East Coast Tuesday then offshore Tuesday night. High pressure will push in behind its associated cold front, briefly, before the next storm system moves across the region Wednesday and Wednesday night. The second storm`s cold front should push across the area Wednesday night. While timing and coverage of rain showers is a little uncertain, the best chance for rain showers and perhaps a thunderstorm will be Wednesday. As the main trough of low pressure pivots across the region Wednesday night into Thursday, cooler and drier air will follow with high pressure building in from the west. Some upslope snow showers could evolve as well through the day Thursday. Another weaker storm system is expected to push into the area on Friday and bring a chance for some rain. By Friday night and Saturday, a strong ridge of high pressure should build in from the northwest. Colder and drier air will ensue.
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&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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Thunderstorms crossing the Baltimore-Washington terminals at this time, some with gusty winds and hail. Activity will clear the area by 22z. There will be a sharp wind shift to the northwest behind this activity. Except a bit of a lull in the winds before colder air rushes in on northwest winds. The peak period likely will be during the evening hours, when 30-35 kt once again possible. During Sunday, it will still be breezy, but not as strong as this evening. Gusts 15-20 kt most likely. Otherwise VFR conditions expected. No major impacts are forecast Monday and Monday night either, although there will be increasing chances for some light rain showers. Mvfr conditions Tuesday into Tuesday night. Ifr and lifr conditions possible Wednesday with the chance of more numerous rain showers or perhaps a rumble of thunder. Mvfr conditions Wednesday night. Winds south 5 knots Tuesday and Tuesday night. Winds southwest 5 to 10 knots Wednesday and Wednesday night.
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&& .MARINE...
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Gale Warning in effect. Sharp cold front will move eastward this afternoon, accompanied by strong showers and storms with 50+ kt wind potential as well as hail. Severe Thunderstorm Watch in effect until 8pm. Special Marine Warnings will be issued as necessary. Winds shift to west, with continuing gusts near gale force possible through the evening. The main story is the sudden onset, which may catch boaters off guard after the mild morning. SCA conditions then continue through Sunday afternoon. Brief lull Sunday night with high pressure, but southerly winds could again reach SCA criteria on Monday into Monday night. System moving through Tuesday/Wednesday may result in continued SCA conditions as southerly flow continues.
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&& .CLIMATE... Record high maximum and minimum temperatures for February 25: BWI 83F (1930), 52F (1930) DCA 84F (1930), 54F (1891) IAD 79F (2000), 47F (2000) 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 24th) DCA: 47.1 BWI: 43.7 IAD: 44.5 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 24) DCA: 43.7 BWI: 40.3 IAD: 40.7 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 24th) DCA: 0.16 BWI: 0.46 IAD: 0.25 && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 1 AM to 4 PM EST Sunday for ANZ530>543. Gale Warning until 1 AM EST Sunday for ANZ530>543. && $$ SYNOPSIS...RCM NEAR TERM...HTS SHORT TERM...ADS LONG TERM...KLW AVIATION...HTS/KLW MARINE...HTS/RCM CLIMATE...BAJ/DFH/RCM

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