Area Forecast Discussion
Issued by NWS Sterling, VA

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767 FXUS61 KLWX 140219 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 919 PM EST Fri Jan 13 2017 .SYNOPSIS...
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A frontal system will stall near the area through the weekend. A cold front will approach the area before weakening during midweek.
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&& .NEAR TERM /THROUGH SATURDAY/...
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1040mb+ surface high will move eastward from the Great Lakes and into New England tonight and on Saturday. This is causing low level cold air to seep southward and into our region tonight. Temperatures have fallen into the 30s across the northern third of the area and will continue to fall through the rest of the night. By morning, expecting temperatures near or just below freezing in most locations, with the exception of parts of central VA and southern MD where mid 30s likely. Waves of light precipitation will move across the area tonight and into Saturday, and with low level and surface temperatures near freezing, this will set the stage for a light mixed precipitation event. With marginal temperatures at onset, precip likely to start out as rain/sleet, with freezing rain where it does fall below freezing, and possibly some snow, mainly across Maryland and West Virginia. Precipitation will then transition to a mix of sleet and freezing rain/rain on Saturday. Models currently differ on depth of low level cold and this will determine on how much sleet versus freezing rain occurs. Temperatures then may rise slightly Saturday afternoon, with some places going back to plain rain before tapering off to light precip/drizzle. With light precip amounts, marginal cold, and warm ground temperatures before the event, ice amounts won`t be excessive for most locations. Highest accumulations likely across the higher elevations where coldest layer is modeled between 1000 and 3000 feet in elevation. Thus total snowfall amounts light, under an inch, and mainly confined to central/northern Maryland and portions of WV. Ice accumulations generally a trace to a tenth of an inch for most locations in the advisory area, except up to two tenths across the higher terrain. DC/Baltimore metros a trace to a few hundredths.
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&& .SHORT TERM /SATURDAY NIGHT/... Precip will become more spotty Sat night with temps slowly rising. There could be a few spots along the Mason-Dixon line that remain below freezing Sat night, but most areas will be above freezing. && .LONG TERM /SUNDAY THROUGH FRIDAY/... High pressure will be centered to our northeast while a frontal boundary will be to our southwest. The boundary stalls while the high pressure moves to our east. Some guidance suggest that the boundary will be closer to our CWA, increasing PoPs over our region, while some other guidance keeps us dry. It is expected that the boundary will lift north as a warm front on Tuesday followed by a cold front on Wednesday. Guidance is again in disagreement with what will happen with the front. Some guidance stalls it to the south while other pushes it east and away from us, so one dryer scenario than the other. Temperatures will be near normal on Monday, followed by a warming trend Tuesday into Wednesday. We have to see what will happen with the Wednesday cold front. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
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VFR conditions this evening will deteriorate into MVFR/IFR, possibly LIFR, during the overnight hours and Saturday/Saturday night as low clouds and light mixed precipitation moves overhead. Icing concerns exist at MRB/IAD/BWI/MTN, and to a lesser extent, DCA. CHO has lowest risk of seeing freezing rain. Area should then begin to dry out with improving conditions Sunday, before additional precip is possible Sunday night. Frontal boundary near our region could bring some precipitation on Monday. Warm front lifts on Tuesday and cold front moves through on Wednesday. Therefore precipitation is still possible through Wednesday possibly bringing sub-VFR conditions.
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&& .MARINE...
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Northerly winds below SCA will continue tonight before becoming light and variable Saturday and Saturday night. Frontal boundary near our region could bring some precipitation on Monday. Warm front lifts on Tuesday and cold front moves through on Wednesday. Therefore precipitation is still possible through Wednesday, while winds are expected to stay below threshold.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Winter Weather Advisory from midnight tonight to 6 PM EST Saturday for DCZ001. MD...Winter Weather Advisory from midnight tonight to 6 PM EST Saturday for MDZ003-004-013-501>504. Winter Weather Advisory from 4 AM to 6 PM EST Saturday for MDZ005-006-011-014-505>508. VA...Freezing Rain Advisory from midnight tonight to 6 PM EST Saturday for VAZ025-026-507-508. Winter Weather Advisory from midnight tonight to 6 PM EST Saturday for VAZ027>031-040-052>054-501-502-505-506. Freezing Rain Advisory until 6 PM EST Saturday for VAZ503-504. WV...Winter Weather Advisory from midnight tonight to 6 PM EST Saturday for WVZ050>053-055-502>504. Freezing Rain Advisory until 6 PM EST Saturday for WVZ501-505- 506. MARINE...Small Craft Advisory until 1 AM EST Saturday for ANZ533-534- 537-542-543.
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&& $$ SYNOPSIS...LFR/MM NEAR TERM...MM/LFR SHORT TERM...IMR LONG TERM...IMR AVIATION...MM/IMR/LFR MARINE...MM/IMR/LFR

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