Area Forecast Discussion
Issued by NWS Sterling, VA

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661 FXUS61 KLWX 250033 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 833 PM EDT Sat Jun 24 2017 .SYNOPSIS... High pressure will build west of the area through the rest of the weekend and into next week as a series of weak cold fronts cross the region. These fronts will bring with them little if any precipitation. The sprawling surface ridge will then cross the region Wednesday and settle over the western Atlantic Ocean late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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A couple showers have popped up over West Virginia this evening. An isolated shower cannot be ruled out in the Allegheny and Potomac Highlands this evening...but most places will end up dry. Latest mesoanalysis shows little to no instability east of the Allegheny Highlands. High pressure will continue to build from the west tonight. A west to northwest flow ahead of the high will usher in dry and comfortable conditions for this time of year. Min temps will range from the 50s in the Allgheny and Potomac Highlands...to the 60s across most other locations...to the low 70s in downtown Washington and Baltimore.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... Upper level troughing over the northeastern US will define the rest of the weekend and early week period, with a sprawling surface high developing over the Midwest and Ohio Valley. This will allow several weak frontal features to drop through the northeast states during this time. The first will cross portions of the northeast on Sunday. For the most part this will remain off to our northeast, with westerly flow and a mix of sun and clouds. Highs from 75-85F. Fair weather continues Sunday night, with temperatures cooling off into the 50s/60s. The next weak frontal passage will occur on Monday, bringing with it additional cumulus and perhaps a few isolated showers. Highs Monday in the 70s to around 80F, dropping off at night into the 50s to around 60F. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Upper level trough and its associated surface reflection will slide east, and its axis will move across our area Tuesday. This trough could create enough instability to allow for some showers and thunderstorms mainly Tuesday afternoon. Temperatures will be below normal with highs in the 60s and 70s, and lows in the 40s and 50s. Surface high pressure builds east Tuesday night, then moves offshore late Wednesday, settling as a Bermuda high into Thursday as flow becomes more southerly. Temperatures will be on the rise and dry conditions continue into Thursday night. Guidance suggest that upper level energy could bring showers and thunderstorms over parts of our area Friday into Saturday. Cold front approaches from west on Saturday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/...
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VFR expected through the forecast period. Gusts out of the west/northwest to around 20 knots likely Sunday and Monday. An isolated shower could also occur Monday with a weak cold front, but coverage will be extremely limited. Scattered showers and thunderstorms possible Tuesday as upper air disturbance moves through, which could cause periods of sub- VFR conditions. VFR conditions return Tuesday night into Thursday with high pressure building in.
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&& .MARINE...
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Winds have diminished this evening. A pressure surge behind a trough is expected late tonight. Northwest winds may approach SCA criteria along the Bay and lower Tidal Potomac River. However...confidence is too low for an SCA at this time since the surge will be weak. Will continue to monitor overnight. Additional gusts up to about 20 knots likely Sunday afternoon/evening across the northern Chesapeake Bay, so have issued a Small Craft Advisory from 1 PM through 10 PM. As cooler air moves in over warmer water temperatures Sunday night, increased mixing may lead to these winds persisting through Sunday night...but confidence for an advisory is too low at this time since the pressure gradient will be weak. Additional gusts near SCA criteria may occur Monday and Monday night with persistent west-northwest flow and weak frontal passages. Scattered showers and thunderstorms possible Tuesday as upper air disturbance moves through. Conditions improve Tuesday night with high pressure building in and weather remaining dry into Thursday. Winds gusts will be below the small craft advisory criteria Tuesday through early Thursday. Wind gusts will increase Thursday afternoon.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory from 1 PM to 10 PM EDT Sunday for ANZ530>532-538>540.
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&& $$ SYNOPSIS...MM NEAR TERM...BJL/MM SHORT TERM...MM LONG TERM...IMR AVIATION...BJL/MM/IMR MARINE...BJL/MM/IMR

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