Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 200803 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 403 AM EDT Fri Apr 20 2018 .SYNOPSIS...
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Strong high pressure over the Upper Midwest will migrate eastward into the Northeast by Sunday before moving offshore Monday. Low pressure will approach the area from the southeast U.S. during the middle of next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Mostly clear skies being observed early this morning with temperatures falling in to the 30s to near 40 degrees across the CWA. Winds have dropped off appreciably west of the metro areas as the gradient relaxes between low pressure over Nova Scotia and high pressure sliding its way south and east from the upper Midwest. Couple the light winds and clear skies, this sets up prime conditions for temperatures to drop near and below the freezing mark this morning. A Freeze Warning remains in effect until 9am for locations west of I-95, extending westward to the I-81 corridor. As strong high pressure builds over the Great Lakes region today, we will see winds pick back up as mixing increases later this morning. Winds won`t be nearly as gusty as yesterday, but expect gusty northwest breezes of 20 to 30 mph through this evening, before winds subside. Temperatures through tonight will continue the below normal trend, topping out today generally in the middle 50s to near 60 degrees, while the warmest locations across the Central Foothills and the Northern Piedmont of Virginia will extend in to the 60s. Lows tonight will fall back in to the 30s, but remain a touch warmer than this morning. A Freeze Watch is in effect tonight for counties surrounding the I-81 corridor, including portions of north central Maryland and the Shenandoah Valley.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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The weather pattern this weekend will be dominated by the aforementioned area of high pressure to our north, delivering dry conditions, light winds, and slowly moderating, yet still below normal temperatures for the middle of April. Expect some high to mid level clouds to move overhead for the latter half of Saturday and persisting into Sunday as a jet max and some mid level energy crosses the northern portion of our CWA. Highs will range in the lower to middle 60s, with lows bottoming out in the upper 30s to lower 40s.
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&& .LONG TERM /MONDAY THROUGH THURSDAY/...
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Strong sfc high pressure over the Northeast Mon will move offshore in the afternoon with an easterly flow developing late Mon night resulting in low clouds with light rain or drizzle along and west of the Blue Ridge. Stratiform rain will overspread the area later Tue into Wed as easterly flow strengthens detween departing high and sfc low lifting from the Southeast into the Mid-Atlantic. The low will begin to move away from the area during the second half of the week with a gradual drying trend expected, but it won`t be completely dry.
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&& .AVIATION /08Z FRIDAY THROUGH TUESDAY/...
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VFR conditions prevailing through the weekend as high pressure builds to our north. Gusty northwest winds expected to return this morning as mixing commences, gusting to around 25 knots during the day before abating late this afternoon and evening. Winds will remain light through the weekend, mainly northerly on Saturday, then veering to the northeast Sunday, then east southeast through Sunday night. MVFR conditions will begin to develop Mon night as easterly flow develops. Widespread clouds with stratiform rain is expected Tue into Wed with flight restrictions likely.
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&& .MARINE...
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Small Craft conditions will continue today with gusty northwest winds expected over the waters. Winds are forecast to subside this evening as the pressure gradient relaxes and high pressure over the Great Lakes wedges overhead. One exception to this will be the lower Chesapeake, where winds will likely reach marginal SCA conditions after midnight, continuing towards daybreak. With high pressure dominating the weather pattern through the weekend, light northerly winds are expected with no advisories or headlines anticipated.
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&& .FIRE WEATHER...
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RH`s will drop below 30% today south of Fauquier county with lowest Rh`s in Albermarle, Nelson, and Augusta counties. In this area, the winds will be 10 kt or less. So, no SPS warranted.
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&& .TIDES/COASTAL FLOODING...
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Early to middle of next week a decent east to southeast flow will develop which will result in water levels rising. Would expect minor coastal flooding in the Tue-Wed time frame.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Freeze Watch from late tonight through Saturday morning for MDZ003>006-507. Freeze Warning until 9 AM EDT this morning for MDZ003>006- 503>508. VA...Freeze Watch from late tonight through Saturday morning for VAZ025>031-507-508. Freeze Warning until 9 AM EDT this morning for VAZ025>031- 036>040-050>053-055-056-501-502-505>508. WV...Freeze Watch from late tonight through Saturday morning for WVZ051>053. Freeze Warning until 9 AM EDT this morning for WVZ051>053. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ530>543. Small Craft Advisory from 2 AM to 8 AM EDT Saturday for ANZ534- 543.
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&& $$ SYNOPSIS...LFR NEAR TERM...BKF SHORT TERM...BKF LONG TERM...LFR AVIATION...BKF/LFR MARINE...BKF/LFR FIRE WEATHER...LFR TIDES/COASTAL FLOODING...LFR

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