Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250130 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 930 PM EDT Mon Jul 24 2017 .SYNOPSIS...
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A cold front will pass through the area tonight. High pressure will build into the Mid Atlantic Tuesday before moving offshore Wednesday. Another cold front will approach the area Thursday before passing through Friday into Friday night. High pressure is expected to return for the weekend.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Storms that developed in PA have outrun the cold front, which looks to be pushing across the Alleghenies at 9 PM. The southern extent of this line is currently moving across north central MD. The 00Z IAD sounding shows 3000 J/kg of SBCAPE and about 40 kt of 0-6km shear, so the attendant severe threat (localized damaging wind) is not a surprise. However, a mid level stable layer is likely otherwise inhibiting storm development. Thus it`s uncertain if any storms will develop along the outflow to the south (affecting DC and areas to the southeast). While the HRRR has been suggesting it`s possible, the 00Z run backed off. Will have to watch radar, and have maintained chance POPs in the forecast through 1 AM. After that time, the cold front will likely have pushed through most of the CWA except perhaps southern MD. Afterwards some pretty nice weather for late July - the climatologically hottest part of the year. Dewpoints will drop into the lower to mid 60s by sunrise. Skies will be mostly clear by morning. Lows west of I-95 will be in the mid to upper 60s, lower 70s east.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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This will lead into a Tuesday with plenty of sunshine, dewpoints in the lower 60s, and air temperatures reaching the lower to mid 80s. Pleasant weather continues Tuesday night with lows in the mid 60s. Wednesday will see moisture begin to creep back into the Mid Atlantic as high pressure moves offshore. Highs will reach the lower to mid 80s. And with the return moisture lows will not be as cool, falling to the upper 60s/lower 70s.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/... Warm front lifts back north through the area early Thursday, which will bring a return to the heat and humidity...as highs climb back near 90F and dewpoints rise back into the 70s. Increasing chances for showers and thunderstorms late Thursday into Friday as cold front and its associated upper-level trough approach and then cross the area. High pressure builds into the area behind the front for the weekend into early next week. Though, low pressure developing along the front to our south could bring some precipitation back into SE portions of the area Sunday. However, that is not the favored solution at this point. Otherwise, remaining dry with highs in the M80s and dewpoints in the 60s. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/...
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The thunderstorm threat will be exiting the Baltimore area between 10 and 11 PM. While no storms are currently targeting DCA, will leave VCTS mention in case a storm fires along the outflow. Cold front should then cross within a few hours of midnight with a wind shift to the northwest. High pressure will affect the area Tuesday and Wednesday. Will have to watch for low cloud potential with onshore flow early Wednesday morning. Showers and thunderstorms with brief flight restrictions are possible ahead of a cold front mainly late Thursday into Friday. Improving conditions into the weekend as high pressure builds into the area.
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&& .MARINE...
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Strong storms will affect northern portions of the Bay through late evening. Cold front will then push through after midnight. Some guidance hints at SCA potential in NW flow through Tuesday morning. Will evaluate that threat over the next couple of hours. Otherwise lighter winds through Wednesday with high pressure. A cold front will approach the waters Thursday into Thursday night before passing through Friday. Showers and thunderstorms are possible ahead of the front...especially late Thursday into Friday. A Small Craft Advisory may be needed for portions of the waters Thursday and Friday. Improving conditions into the weekend as high pressure builds into the area.
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&& .TIDES/COASTAL FLOODING...
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Straits Point may approach minor flood levels for the overnight high tide cycle if water levels do not drop.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ UPDATE...ADS PREVIOUS...WOODY!/MSE

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