Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 190148 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 848 PM EST Thu Jan 18 2018 .SYNOPSIS... High pressure will build south of the area through the weekend. A cold front will cross the area early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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A 1031mb high pressure center resides over the Gulf Coast states this evening, extending its northeastern flank over our region. This expansive area of high pressure is responsible for clear skies for most locations residing east of the Mississippi River. Winds have been subdued for the last few hours and will continue to trend light to calm across the much of the area overnight. Combine this with clear skies, expect prime radiational cooling conditions tonight. We`ve already seen some of our favored radiational cooling locations dip in to the mid to upper 20s early this evening. With dewpoints in the single digits to low teens across the area, this leaves plenty of room for temperatures to bottom out in the mid to upper teens for most, with locations near our city centers holding in the low to middle 20s. On going forecast is in good shape with no major changes needed.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... Warm advection should be underway Friday, with little tangible weather. Aside from perhaps some high clouds, it will largely be a temperature forecast. Readings should get into the 40s Friday (without the winds) and 50s Saturday. Lows will drop into the 20s Friday night and near freezing Saturday night. As an upper disturbance tracks along the Gulf coast Saturday- Saturday night, some moisture could spread north with isentropic lift up the mountains. At this point, there is light qpf (at best)...so PoPs are subsequently low (chance). Will need to keep an eye on temperatures though. Believe that there will be enough warm advection to preclude freezing rain, but a few GEFS ensemble members do have subfreezing air just east of where the meager PoPs will be. And deterministic output also depict a close call. PoPs are only for the western fringe zones, and are only 20-30%, but did introduce rain or freezing rain overnight...just in case. && .LONG TERM /SUNDAY THROUGH THURSDAY/... High pressure will be near the South Carolina coast Sunday, with a warm front lifting northward to our west. An area of low pressure will develop along the tail-end of this warm front over the central Plains. The low is expected to move toward the Great Lakes region Sunday night through Monday night. With that, the warm front will bring us a chance for a rain showers along the Mason-Dixon region and the Appalachian Front Sunday night and Monday. The increased chance for rain showers will be Monday night with a cold front passage. Temperatures will be above normal Sunday night through Monday night. High temperatures could reach the 60s Monday ahead of the cold front. Rain showers could linger on Tuesday on the back side of the cold front. Colder and drier air will move in behind the front as well. Temperatures will be about 10 degrees cooler than the day before due to frontal passage. High pressure will regain control of the region with the chilly January air but plenty of sunshine Wednesday through Thursday. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/...
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VFR conditions will dominate heading in to the weekend. Light winds forecast overnight in to Friday, remaining at 10 knots or less, residing out of the west to southwest through Saturday night. VFR conditions continue Sunday through midday Monday. MVFR to briefly IFR conditions possible with rain showers late Monday and Monday night.
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&& .MARINE...
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With a ridge of high pressure building over our region, light winds will prevail overnight with no headlines expected. Wind flow will back southwest Friday, and will remain there at 10 kt or less through Monday.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...None.
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&& $$ SYNOPSIS...HTS NEAR TERM...BKF SHORT TERM...HTS LONG TERM...KLW AVIATION...BKF/HTS/KLW MARINE...BKF/HTS/KLW

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