Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 140015 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 815 PM EDT Wed Sep 13 2017 .SYNOPSIS...
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The remnants of Irma will move into Pennsylvania from the Ohio Valley through Thursday. High pressure will build into our region during the weekend.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Clouds have cleared this evening. This should allow for at least patchy fog to develop this evening. Clouds are beginning to move across the mountains from the west as of 8 PM, and these will spread across the area during the overnight as low pressure (formerly known as Irma) drift towards the area. A few sprinkles/showers are possible late during the overnight, as well, but cut PoPs back due to large-scale subsidence and dry air above the boundary layer. Otherwise, previous forecast on track with no major changes needed.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... Thursday the low will become an open wave over PA bringing chances of rain to the entire area; the farther north in the forecast area the better the chances will be. QPF is expected to be 1/4 inch or less. Highs 75 to 80. Shower chances will be decreasing Thursday evening as the wave tracks into New England. Skies should be clearing late. Lows in the lower to mid 60s east of the mountains...mid to upper 50s west. There won`t be any front sweeping the moisture away Thursday night and Friday, so would not be surprised to see fog development Thursday night and Cu development Friday. Still - these should both be dry. Highs Friday again around 80. No problems expected Friday night either - lows in the 60s. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Surface high pressure will remain centered near the New England Coast for the weekend through the middle portion of next week. An upper-level ridge is most likely to remain overhead during this time as well. Subsidence from the upper-level ridge will allow for temps to remain above climo during this time. Areas of low clouds and fog are possible during the overnight and morning hours each day due to low- level moisture associated with a northeast flow. A couple popup showers are possible as well...but coverage should remain isolated to widely scattered due to the upper-level ridge in place. Will continue to watch Jose out in the Atlantic. There is a possibility that it could affect the east coast of the United States during the middle portion of next week...and this would obviously have an impact on our forecast. For the latest information regarding Jose...please refer to the National Hurricane Center`s website hurricanes.gov. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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Fog is likely tonight at IAD/MRB/CHO/MTN, possible at BWI and DCA. Showers expected Thursday afternoon and early evening. Clearing is expected after midnight which could set up fog development by Friday morning. High pressure most likely remain over the area Saturday through Monday. Areas of low clouds and fog are possible during the morning hours each day Saturday through Monday...otherwise VFR conditions are most likely.
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&& .MARINE...
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Winds to remain below SCA values through Friday, though will have to watch for a few sporadic gusts to around 20 knots as a weak low-level jet moves overhead late tonight into Thursday morning. High pressure will remain over the waters for Saturday through Monday. Marine hazards are unlikely during this time. Continuing to watch Jose out in the Atlantic. This has the potential to impact the east coast of the United States...but not until the middle portion of next week. For more information regarding Jose...please refer to the National Hurricane Center`s website hurricanes.gov.
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&& .TIDES/COASTAL FLOODING...
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Hoisted a Coastal Flood Advisory for St. Mary`s and Anne Arundel Counties in anticipation of minor flooding at Straits Point and Annapolis during this evening`s high tide cycle. Anomalies should begin to slowly decrease through Thursday, so no additional flooding is forecast (especially since the Thursday high tide cycle is the lower of the two).
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Coastal Flood Advisory until 2 AM EDT Thursday for MDZ014. Coastal Flood Advisory until 10 PM EDT this evening for MDZ017. VA...None. WV...None. MARINE...None.
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&& $$ SYNOPSIS...WOODY!/DFH NEAR TERM...WOODY!/DFH SHORT TERM...WOODY!/DFH LONG TERM...BJL AVIATION...BJL/WOODY!/DFH MARINE...BJL/WOODY!/DFH TIDES/COASTAL FLOODING...DFH

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