Area Forecast Discussion
Issued by NWS Sterling, VA

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596 FXUS61 KLWX 161845 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 245 PM EDT Sat Sep 16 2017 .SYNOPSIS...
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High pressure will dominate the region through Sunday. Hurricane Jose is forecast to move north along...but well offshore of... the Atlantic coast early next week. See the National Hurricane Center bulletins for the latest information on Jose. High pressure over New England may extend into our area late next week.
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&& .NEAR TERM /THROUGH TONIGHT/...
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A ridge of high pressure will remain over the eastern United States through tonight. A small weakness in the ridge remains over our area in the form of an upper-level low. The upper-level low is weak...but there are enough height falls for limited instability this afternoon and early evening. An easterly flow will usher in moisture from the Atlantic as well...and that can be seen currently with dewpoints in the 60s for most locations. Unseasonably warm conditions will continue through late this afternoon with max temps in the lower to middle 80s across most locations. Isolated to widely scattered popup showers are expected through early this evening due to daytime heating and limited instability. Latest forecast soundings show that convection will be low topped due to the large scale subsidence from the upper- level ridge. Therefore...left lightning out of the forecast at this time and any showers that do occur are expected to be brief. Any showers should diminish around sunset. Plenty of moisture underneath the nocturnal inversion will result in some fog tonight. Fog may be dense...especially in rural areas and sheltered valleys.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
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Surface high pressure will wedge into the area from the New England Coast Sunday while a weak upper-level trough remains overhead within the longwave upper-level ridge. More warm conditions are expected for this time of year with isolated to widely scattered popup showers. The best chance for showers will be near and west of the Blue Ridge and Catoctin Mountains where terrain circulation may serve as a lifting mechanism. Jose will track north off the Mid-Atlantic Coast Sunday night through Monday night. This system is most likely to stay far enough offshore to prevent any significant impact on our weather. However...an east to northeast flow around this system will continue to usher in more moisture across our area. A few outer band of showers cannot be ruled out...but much of the time is likely to turn out dry. Please refer to the National Hurricane Center for updates on the forecast regarding Jose.
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&& .LONG TERM /TUESDAY THROUGH FRIDAY/...
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Hurricane Jose will be moving north on Tuesday, well east of the Mid-Atlantic coast. Confidence has increased in its track, which currently keep its center well offshore with minimal impacts to our CWA. Current concerns are minor coastal flooding and/or wind gusts between 30 to 40 mph over the Chesapeake Bay. The National Hurricane Center is issuing advisories on Hurricane Jose and can be found at the following website: http:/www.nhc.noaa.gov. Jose will continue to track north and then northeast away from our region Wednesday into Saturday as high pressure builds into our area. Some afternoon showers possible Wednesday into Friday due to upper level energy.
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&& .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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VFR conditions are expected through this evening. A popup shower cannot be ruled out through sunset. Areas of fog are expected overnight into Sunday morning. Fog may be locally dense with IFR or subIFR conditions possible. The best chance for dense fog will be across KCHO and KMRB...but it is possible across the other terminals as well. Kept the lowest vsbys forecasted in the western terminals for now where confidence is highest. A weak onshore flow will continue through Monday night. Areas of low clouds and/or fog are possible during the overnight and morning hours each day. Tuesday maybe periods of sub-VFR conditions at times due to showers and/or thunderstorms, with maybe an increase in winds as Jose moves away from us. Wednesday into Thursday mostly VFR conditions expected with high pressure building in.
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&& .MARINE...
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An onshore flow will continue through Monday...but wind speeds should remain below SCA criteria. Jose is most likely to pass by well offshore Monday night through Tuesday night. A Small Craft Advisory will likely be needed for portions of the waters during this time. Will have to watch Jose...any shift in the track will have a significant impact on wind speeds. See the National Hurricane Center for the latest on the forecast of Jose. Weak high pressure may return for late next week.
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&& .TIDES/COASTAL FLOODING...
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A light onshore flow will continue through tonight. Elevated water levels are expected. Most areas should have water levels just below minor thresholds during the preferred high tide cycle tonight. However...latest forecast has minor flooding at Straits Point so a Coastal Flood Advisory has been issued. Later Sunday and especially Monday, the approach of Jose may further elevate water levels, resulting in minor flooding at sensitive sites. The nighttime tide cycle is astronomically preferred. Depending on how close the storm gets, moderate is not impossible, but uncertainty on this is very high at the moment.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...Coastal Flood Advisory from 10 PM this evening to 3 AM EDT Sunday for MDZ017. VA...None. WV...None. MARINE...None.
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&& $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...IMR AVIATION...BJL/IMR MARINE...BJL/IMR TIDES/COASTAL FLOODING...BJL

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