Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 271412 AAA AFDLWX Area Forecast Discussion...UPDATED National Weather Service Baltimore MD/Washington DC 1012 AM EDT Tue Jun 27 2017 .SYNOPSIS... A sharp upper level trough will move across the region late today. High pressure builds over the area Wednesday before moving offshore Thursday. Warm conditions expected towards the end of the week and through the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Sharp trough axis will move across the area this afternoon and help trigger scattered showers and t-storms. Moisture and CAPE are limited, but plenty of large scale forcing to overcome these negatives. Best coverage is expected along the I-95 corridor where low-level moisture is higher due to proximity to the water. Gusty winds will be primary threat due to inverted-V soundings and large amounts of downdraft CAPE. Convection will shift east quickly after 21Z with precip ending. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... The surface high pressure center crosses the LWX CWA Wednesday morning. Return southerly flow develops Wednesday afternoon with a gradual return to summerlike conditions. Pressure gradient looks light enough for good radiational cooling Wednesday night. Max temps around 90F on Thursday with dewpoints rising into the 60s. && .LONG TERM /FRIDAY THROUGH MONDAY/... High pressure will have moved well offshore by Friday. This will allow warmth/humidity to stream into the Mid Atlantic. Upper level ridge will not bring the east coast especially high heights so expect to see highs around end-of-June climo norms of near 90. Low pressure is expected to spin over Ontario/Quebec this weekend. This will allow a weak cold front/trough to be in the vicinity of the Mid Atlantic which could provide a focus for shower/thunderstorm activity, although by no means should the weekend be a washout. Looking out to the 4th of July - there are differences between the Euro and GFS. One thing seems certain is that the possibility of it being an extremely hot day does not look to be in the cards. Euro shows east coast "in between short waves" while GFS has a short wave approaching the Appalachians Tuesay night. We have a chance of showers/thunderstorms in the forecast but we`ll continue to monitor in the coming days. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... VFR prevails through the week as high pressure slowly builds from the west. Passing shower/isolated thunderstorm both this morning and later this afternoon across the DC metros ahead of a cold front. High pressure overhead Wednesday with return southerly flow into the weekend. Majority of Friday/Saturday should be VFR. There will be potential for showers/thunderstorms - especially Saturday, which could drop conditions briefly below VFR. && .MARINE... Considering an SCA for today or MWS for later this afternoon and tonight. SMWs may be required later this afternoon. Return southerly flow begins Wednesday night as the high shifts to Bermuda. Winds expected to be below SCA values Friday/Saturday. Showers/isolated thunderstoms will be possible on the waters Saturday. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ Update...LFR Products...BAJ/WOODY!

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