Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 200721 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 321 AM EDT Thu Apr 20 2017 .SYNOPSIS...
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High pressure off the coast will move further east today. A cold front will drop into the Mid Atlantic Friday afternoon. Weak high pressure builds over the area Friday night before low pressure impacts the area Saturday night and Sunday.
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&& .NEAR TERM /TODAY/...
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Have cut back on PoPs for the first half of today. A warm front extends from low pressure over IA over MI and into the northeast US. Showers can be seen on regional radar across PA but these are not making any southward progress. The potential exists for showers/thunderstorms this afternoon. Coverage would be scattered. Expecting quite a bit of cloud coverage today. This will limit CAPE, and hodographs show only weak shear. Highs around 80.
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&& .SHORT TERM /TONIGHT THROUGH SATURDAY/...
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Boundary appears to be hanging around right into the weekend. This will lead to extensive cloud cover from Thursday night right through Saturday. The better chance for rain looks to be during Saturday as low pressure forms over the TN Valley and progresses east during the late afternoon. Highs look to reach the low 80s over much of the area Friday, but with the extensive cloud cover/rain Saturday highs will only reach climb to the low/mid 60s.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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Unsettled weather looking likely for much of the weekend and into next week. An area of low pressure will move from the lower Mississippi River Valley Saturday to the Mid-Atlantic/Southeast coastline by Sunday, tracking eastward along a baroclinic zone. There remains some discrepancies between model suites as to how far north/south the zone becomes established and therefore the low track and area of steadiest/heaviest rainfall, but the setup should be favorable for a period of overrunning rain Saturday into Sunday. Energy will likely be slow to depart the east coast in the Monday/Tuesday timeframe, and with low pressure possibly lingering offshore as high pressure builds into New England, this may promote onshore flow, cool temperatures, lingering clouds and chances for showers. By Wednesday, should see more of a southerly flow develop as a low pressure system moves through the Great Lakes. This should bring warmer temperatures, as well as the possibility for additional showers, especially west. Temperatures will be on the cooler side in the extended period, with highs likely holding in the 50s for much of the region Sunday with rain/clouds. Some improvement Monday/Tuesday, with highs generally in the 60s. Warmest day looks to Wednesday where 70s likely. Lows during this time period mainly 40s to around 50F.
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&& .AVIATION /TODAY THROUGH MONDAY/...
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Currently across the northern part of the forecast area ceilings are in the 010-015 range while CHO is over FL 100. Believe ceilings will lower further south as the morning progresses while at the major airports MVFR will be the predominant condition. Improvement is expected during Friday but then degrading by Saturday afternoon. Low clouds and periods of rain Saturday night and Sunday will likely bring widespread sub-VFR reductions to both ceilings and visibilities. Low clouds and areas of light showers may persist into early next week.
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&& .MARINE...
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Winds remaining below SCA values today/tonight. Rain is expected for the waters Saturday. Generally sub-SCA conditions expected Saturday night and Sunday. SCA conditions possible Monday with increasing northeasterly flow.
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&& .TIDES/COASTAL FLOODING...
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Water levels will continue to be elevated today. Departures will be running about a foot above normal. Some Action Stages will be threatened.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ PRODUCTS...WOODY!/MJM

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