Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 130830 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 330 AM EST Mon Feb 13 2017 .SYNOPSIS...
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Low pressure will rapidly strengthen off the New England coast today. High pressure will briefly return for later tonight into Tuesday. Another cold front will pass through Wednesday. High pressure will build overhead late in the week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Scattered snow showers are occurring early this morning across the Allegheny Front as well as northern Maryland...extreme northern Virgina and the eastern panhandle of West Virginia. This is in response to strong cold advection and shortwave energy associated with an upper-level low well off to our north. This activity should dissipate later this morning as the subsidence inversion lowers. Accumulating snow is expected for locations along and west of the Allegheny Front due to an upslope flow. Low pressure has begun to rapidly intensify off the New England coast and this will continue through midday before gradually moving out to sea. A strong pressure gradient between the low off the New England coast and high pressure over the Midwest will continue to cause windy conditions today. Will continue with a High Wind Warning for the ridge tops as well as the Baltimore and Washington Metropolitan areas. The strongest winds are expected shortly after sunrise where the mixing will increase and line up with the strongest winds aloft. Wind gusts of 50 to 60 mph are expected. Latest NAM/GFS bufkit show around 50 knots at the top of the mixing layer through late this morning. Elsewhere...gusts around 35 to 50 mph are expected and a Wind Advisory is in effect for other locations except central Virginia. Winds should gradually diminish this afternoon as the gradient slowly weakens in response to the low moving out to sea. Wind headlines may be able to be dropped during the mid to late afternoon hours. Sunshine is expected across most locations with max temps ranging from the 20s along the ridge tops of the Allegheny Highlands...to the middle and upper 40s near Washington and Baltimore....to near 50 in central Virginia. High pressure will buiSCA winds likely Thursday in cold air advection behind frontal boundary. Winds slacken late Thursday into Friday as high pressure builds into the area. ld overhead tonight and winds will continue to diminish. However...it will turn out seasonably chilly.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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High pressure will move off to the east Tuesday and a southwest flow will allow for a milder afternoon with max temps in the 50s for most locations. A cold front associated with the northern stream of the jet will approach Tuesday night. Southern stream energy should stay mostly to our south during this time. However...there may be enough moisture for a period of rain overnight across southern Maryland and perhaps into portions of central Virginia. Rainfall amounts would be light. For other locations...most areas will remain dry but there will be a few rain or snow showers possible in the Potomac Highlands. The best chance for snow showers will be along and west of the Allegheny Front. Any accumulating snow will be light and confined to locations along and west of the Allegheny Front. The cold front will pass through Wednesday and the upper-level trough in the northern stream of the jet will build overhead Wednesday. Southern stream energy will move off well to our south and east Wednesday. Any leftover rain across our southern areas will end during the morning. Blustery and seasonably chilly conditions are expected behind the front. A few snow showers are possible as well due to the upper-level trough overhead. The best chance for snow showers will be along and west of the Allegheny Front due to an upslope flow. Low pressure will intensify off the New England Coast Wednesday night. More blustery and chilly conditions are expected. With the upper-level trough overhead a few snow showers cannot be ruled out. Again...confidence for snow showers is highest along and west of the Allegheny Front.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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Relatively benign weather through the long term. Cold air advection continues Thursday behind the front...with breezy conditions as NW winds gust near 20-30 mph during the afternoon. Dry nearly everywhere...except along the Allegheny Front...where light upslope snow showers are possible through the evening. High pressure slides to our south Friday...with westerly winds turning southwesterly during the afternoon. This will lead to a warming trend into the weekend as return flow reestablishes itself. Front approaches the area late in the weekend into early next week. Still uncertainty on frontal location...which will ultimately determine temperature spread and precipitation chances. For now went with a model blend until these details become clearer.
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&& .AVIATION /08Z MONDAY THROUGH FRIDAY/...
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Strong northwest winds are expected through this morning. Gusty winds will gradually diminish this afternoon into early this evening. The strongest wind gusts around 45 to 50 knots are expected through this morning. High pressure will build overhead tonight and winds will continue to diminish. VFR conditions are expected for Tuesday through Wednesday night. Gusty northwest winds will return behind a cold front Wednesday into Wednesday night with gusts 25 to 30 knots possible. VFR conditions expected Thursday with NW wind gusts 20-25 knots. VFR continues Friday with lighter winds as high pressure builds into the area.
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&& .MARINE...
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Strong northwest winds will continue for today as low pressure rapidly intensifies to the north. Storm warnings and gale warnings remain in effect for the waters today. The strongest winds will be through this morning before gradually diminishing this afternoon. Winds will continue to diminish tonight as high pressure builds overhead. A southerly flow will develop for Tuesday through Tuesday night as high pressure moves offshore. Winds may be close to SCA criteria...but confidence is too low for a headline at this time. A cold front will pass through the waters Wednesday and gusty northwest winds are expected behind the front through Wednesday night. SCA winds likely Thursday in cold air advection behind frontal boundary. Winds slacken late Thursday into Friday as high pressure builds into the area.
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&& .FIRE WEATHER... RH may drop below 30% with sustained winds of 20-30 mph in the central VA Piedmont and central/southern Shenandoah Valley on Monday afternoon. However, fuel moisture is above 10% for most of the area, precluding a fire weather threat. && .TIDES/COASTAL FLOODING...
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Strong northwest winds will continue behind a cold front today. Tidal blowout conditions are likely...especially later today into this evening with anomalies around 1 to 2 feet below normal possible.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...High Wind Warning until 6 PM EST this evening for DCZ001. MD...High Wind Warning until 3 PM EST this afternoon for MDZ501. Wind Advisory until 3 PM EST this afternoon for MDZ003-502. Wind Advisory until 6 PM EST this evening for MDZ016-017. High Wind Warning until 6 PM EST this evening for MDZ004>006- 011-013-014-018-503>508. VA...High Wind Warning until 3 PM EST this afternoon for VAZ025-026- 503-504-507-508. Wind Advisory until 3 PM EST this afternoon for VAZ027>031- 038>040-051-057. Wind Advisory until 6 PM EST this evening for VAZ052-055-501- 502. High Wind Warning until 6 PM EST this evening for VAZ053-054- 505-506. WV...High Wind Warning until 3 PM EST this afternoon for WVZ501>503- 505-506. Wind Advisory until 3 PM EST this afternoon for WVZ050>053-055- 504. MARINE...Small Craft Advisory from 6 PM this evening to 6 AM EST Tuesday for ANZ531>534-537-539>541-543. Storm Warning until 6 PM EST this evening for ANZ530>533-535- 538>541. Small Craft Advisory from 6 PM this evening to midnight EST tonight for ANZ530-535-536-538-542. Gale Warning until 6 PM EST this evening for ANZ534-536-537- 542-543.
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&& $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...MSE AVIATION...BJL/MSE MARINE...BJL/MSE FIRE WEATHER...BJL TIDES/COASTAL FLOODING...BJL

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