Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 141346 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 946 AM EDT Thu Sep 14 2017 .SYNOPSIS...
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The remnants of Irma - over Pennsylvania - will track northeast into southern New England tonight. High pressure will build into the Mid Atlantic for the weekend. Hurricane Jose is presently 1100 miles east of Jacksonville. See National Hurricane Center bulletins for information on Jose.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Water vapor imagery shows a circulation of the remnants of Irma over Pennsylvania. Shower activity over western West Virginia is moving east and expected to reach the Appalachians around 22Z. Late afternoon showers/isolated thunderstorms will be possible in the forecast area. High temperatues this afternoon with be close to average with in the upper 70s to near 80. Although we can`t rule out a lingering shower this evening and overnight, the center of the remnants of Irma should scoot to our east to allow for NVA to evolve to our west. Patchy fog could redevelop tonight due to residual moisture from recent rainfall and places that do clear out. Lows tonight will be in the lower to mid 60s with mid 50s west.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
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Some upper level energy could still rotate around the remnants of Irma on Friday. Although the remnants will be well to our northeast, any energy that drops southward into our region could spawn a couple of showers. Highs will be near 80. Conditions will dry out Friday night with lows in the lower 60s. High pressure will gradually build in from the northwest Saturday and Saturday night. A nearby trough of low pressure over portions of the Delmarva Peninsula could spawn an afternoon shower in parts of southern Maryland, also possible over the Potomac Highlands. Highs in the lower to mid 80s Saturday with lows in the mid 60s Saturday night.
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&& .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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Surface high pressure will be atop the forecast area for much of the extended forecast period. However, the ridging aloft will be situated west of the Appalachians. Hence, heights are rather low and low-level flow is onshore, an artifact of Jose in the western Atlantic. As such, decent CAPE will be able to generate each afternoon, especially Sunday and Monday. Therefore, the forecast will feature isolated/scattered showers and thunderstorms. Since these will be instability-driven, anticipate a rapid demise with sunset. Heights will be higher, and PoPs will be lower by Tuesday-Wednesday. Speaking of Jose, through the forecast period, much of the forecast guidance has consolidated in an offshore solution. However, there are still ensemble members...from both EPS and GEFS...that want to split from the back and make a hard left turn. Thus, it is way too early to state anything conclusively.
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&& .AVIATION /13Z THURSDAY THROUGH MONDAY/...
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VFR conditions at all terminals today. Showers or a brief thunderstorm this afternoon near MRB, IAD, and DCA could reduce conditions to MVFR for a brief period. Winds generally southwest 5 to 10 knots shifting to the west at 5 to 10 knots today. VFR conditions tonight. There could be some patchy fog. VFR conditions Friday and Friday night at all terminals. There could be a passing shower Friday afternoon. Early morning low clouds and fog and late day widely scattered showers and thunderstorms will be possbile Sunday and Monday. Flight restrictions will be possible...the greater confidence of such will be during the morning push.
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&& .MARINE...
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No marine hazards expected today through Friday night. Winds Sunday-Monday will be north/northeast. At this time, the gradient does not look strong enough to support winds much above 10kt.
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&& .TIDES/COASTAL FLOODING...
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Water levels are running a good 3/4 to 1 ft above astronomical normals, which is also about a half foot above ESTOFS/ETSS guidance. The daytime tide cycle will be the lower astronomically. In addition, guidance sugests that water levels will ease slightly. This combination will preclude the need for any Advisories during the day. Hopefully these trends carry over into Thursday night as projected.
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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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&& $$ UPDATE...WOODY! PREVIOUS...KLW/HTS

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