Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 021939 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 239 PM EST Tue Mar 2 2021 .SYNOPSIS...
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High pressure remains in control through this weekend with a brief wave of precipitation possible along the Allegheny front early on Thursday. Mostly Dry conditions expected through early next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Winds are slowly tapering off this afternoon as high pressure slowly builds overhead. Clear skies along with cool conditions are expected to continue through this evening. Although there will be increased mixing today due to mostly sunny conditions, cold air advection aloft will lead to afternoon temps in the low to mid 40s. Light winds along with areas of decent radiational cooling will lead to overnight lows in the 20s to lower 30s but some elevated winds will prevent overnight lows from falling further this evening.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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A split flow aloft will shift eastward on Wednesday with high pressure remaining situated over our region. A shortwave will move south of our region on Wednesday with a surface low impacting parts of southern Virginia and down into the Carolinas. Precipitation from this system will stay well south of our region with temperatures expected to trend upward into the 50s on Wednesday. A shortwave over the upper plains will drop southeastward into the northwest portions of our region late Wednesday into early Thursday. A combination of a west to northwesterly flow along with the lift from the shortwave will lead to some potential wintry mix showers along the Allegheny front. Some freezing rain and snow showers can`t be ruled out with this wave during the early morning periods on Thursday with minimal accumulations expected along the mountains. After the shortwave drops south of our region Thursday morning, high pressure builds back into our region with dry and below average temperatures expected for the rest of the day and evening.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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Dry and seasonably chilly conditions will persist Friday as a region of Canadian high pressure builds overhead. This likely suppresses an area of low pressure to the south on Saturday before heading out to sea. Behind this system, attention then turns to a piece of northern stream energy that will move over the region Saturday night. Current guidance has minimal QPF associated with this feature, but should the piece of energy become stronger, a few rain/snow showers could be possible Saturday night mainly across the western highlands. Confidence in this occurring is low. A broad area of high pressure will keep temperatures closer to seasonal levels Sunday into Monday before moderating Tuesday as southwest flow returns.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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Clear skies along with VFR conditions expected through Thursday. Only aviation considerations will be shifting winds from west today to light out of the south on Wednesday and back to west / northwesterly on Thursday. VFR conditions under northwest winds into Saturday afternoon. Winds could gust to 25 knots Friday into Saturday.
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&& .MARINE...
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SCA conditions will taper off this afternoon with SubSCA conditions this evening. Marginal 18 to 20 knot winds on Wednesday. Small Craft Advisories are likely for Thursday. Northwest winds gusting to 20 knots could result in a SCA Friday into Saturday morning.
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&& .HYDROLOGY...
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The excess runoff from previous rainfall has entered the Potomac River Basin. Flooding is expected across portions of the Potomac River Basin through this evening before water levels subside by Wednesday. An extended period of dry weather is likely to persist for the rest of this week into early next week.
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&& .TIDES/COASTAL FLOODING...
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Runoff of rain and snowmelt from a couple days ago is heading down the Potomac River, and minor flooding appears likely this evening and again Wednesday morning.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 3 PM EST this afternoon for ANZ530>543. Small Craft Advisory from 10 PM this evening to 6 AM EST Wednesday for ANZ531>533-537-539>541. Small Craft Advisory from 10 PM this evening to noon EST Wednesday for ANZ534-543. && $$ SYNOPSIS...JMG NEAR TERM...JMG SHORT TERM...JMG LONG TERM...CPB AVIATION...JMG/CPB MARINE...JMG/CPB HYDROLOGY... TIDES/COASTAL FLOODING...

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