Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 171838 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 138 PM EST Wed Jan 17 2018 .SYNOPSIS...
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A cold front will move offshore tonight. High pressure will build south of the area through the weekend. A cold front may approach the area early next week.
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&& .NEAR TERM /THROUGH THURSDAY/...
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Snow has ended across the area except for a few flurries over the southern most reaches of Maryland. A couple scattered flurries could bump up against the western Allegheny Front tonight in favorable NW flow, but given that moisture is shallow and the moisture source (Great Lakes) are now largely frozen, I doubt there would be much in the way of accumulation. Wouldn`t expected any drizzle, though, given the gusty winds. Stayed on the lower end of guidance for low temperatures tonight, especially where snow is on the ground. Gusty winds will continue into the evening for all areas, and through the night over the ridges. The gusty winds combined with cold temperatures (teens lowlands and single digits highlands) will result in wind chills in the single digits for most areas. The ridgetops are expected to see wind chills of -10 to -20 tonight into Thursday morning, and a Wind Chill Advisory is in effect for these areas. A few wind chill readings of around -10 may be observed in a much more brief/isolated basis over ridges in Hampshire and Hardy Counties in West Virginia and the Catoctins in Maryland, but spatial coverage is too small to include them at this time. There is a low chance of wind gusts of greater than 45 mph late tonight into Thursday across the ridges as well, but held off on a Wind Advisory due to the low probability of the threat. Winds turn more westerly as strong warming commences aloft Thursday (850 mb temperatures rise from -5 to +5 C in about 12 hours). Despite this advection, dry W flow and subsidence behind an upper low to the east likely keep the region mainly sunny Thursday. Downsloping winds could push temperatures in the lowlands well into the 40s.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
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Undercut most guidance for temperatures Thursday night with clear skies and light winds and dew points still in the teens. BUFKIT soundings imply de-coupling at our usual ideal radiational cooling spots. A shortwave passing to the north could result in a modest increase in high clouds Friday, but no precipitation is expected. The moderating trend in temperatures will continue Friday with highs nearing 50 in many places. We will still be under the influence of high pressure, though, so with mainly clear skies and light winds Friday night, temperatures should again drop into the 20s.
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&& .LONG TERM /SATURDAY THROUGH WEDNESDAY/...
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High pressure will continue to settle south of the region over the weekend. A draw of milder air from the south will allow for temperatures to at least reach the 50s. There could be a couple of rain showers in the western mountains as a weak front moves west to east Saturday night into Sunday. High pressure will move east Monday. A cold front will approach from the west and bring a chance of rain showers, mainly in the west and northern areas during the day. By Monday night, the rain shower threat spreads west to east. High temperatures likely reach the 50s once again. Cooler air will move into the region behind the system on Tuesday, with a decreasing chance of rain as high pressure builds back into the region. Highs will be in the 30s and 40s. Wednesday will be even cooler than Tuesday with high pressure reinforcing itself across the region. Highs will be 40s near the Bay but colder in the central and western areas.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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VFR expected through Friday night as high pressure builds to the south. Winds will be NW 10-20 G 25 kts through this evening, then veer more westerly and diminish to around 10 kts through Friday. A few gusts to near 20 kts are possible during the day Thursday. VFR conditions Saturday through Sunday. Sub-VFR possible by Monday as a cold front approaches from the west. Winds light and southwesterly Saturday into Monday before increasing.
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&& .MARINE...
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Gusty NW flow expected through about midnight on all waters, retreating to the open waters during the late overnight. SCA gusts likely for a time (albeit more marginal) for all waters again Thursday. Winds should become light through Friday, and even though there may be a bit of a gradient at times between high pressure to the south and a shortwave passing to the north, waters will be cooler than the air and that should preclude mixing/SCA gusts. No marine hazards expected Saturday through Sunday night. Winds southwest to west 5 to 10 knots each period.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Wind Chill Advisory from 7 PM this evening to 9 AM EST Thursday for MDZ501. VA...Wind Chill Advisory from 7 PM this evening to 9 AM EST Thursday for VAZ503-504-507-508. WV...Wind Chill Advisory from 7 PM this evening to 9 AM EST Thursday for WVZ501-503-505-506. MARINE...Small Craft Advisory until midnight EST tonight for ANZ530-531- 535-536-538>540-542. Small Craft Advisory from 8 AM to 4 PM EST Thursday for ANZ530- 531-535-536-538>540-542. Small Craft Advisory until 4 PM EST Thursday for ANZ532>534- 537-541-543.
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&& $$ SYNOPSIS...DHOF NEAR TERM...DHOF SHORT TERM...DHOF LONG TERM...KLW AVIATION...KLW/DHOF MARINE...KLW/DHOF

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