Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221825 AFDLWX Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 225 PM EDT Tue Aug 22 2017 .SYNOPSIS...
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High pressure is centered well off the North Carolina coast. A cold front over western Ohio will track across the Mid- Atlantic tonight into Wednesday morning. Reinforcing upper level energy will help to push the front offshore and allow for high pressure to build in from the northwest Thursday into Friday.
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&& .NEAR TERM /TONIGHT/...
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Temperatures in the lower 90s and dewpoints in the low 70s have led to another day with CAPEs of 1000-2000. It is a different synoptic situation from yesterday as we have our eyes on a front/line of storms stretching from Ontario to southern IL. Watches are in effect to our west and north. Aside from any isolated cells that fire ahead of the line the main possibility of convection looks to be from around 9 pm over the mountains to after midnight by the Bay. Models have consistent in weakening the cells once these move east of the Blue Ridge. Yes heating will be over/CAPE will be diminishing but think given the amount of energy in the atmosphere still believe severe storms could be possible through midnight. Storms should weaken after midnight with PoPs decreasing from NW to SE. Lows in the mid to upper 60s west of the mountains...low to mid 70s east.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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Showers/isolated thunderstorms will be possible across the southern 2/3 of the forecast area Wednesday. By Wednesday precipitation should be well offshore. Tonight`s fropa will bring an end to this recent heat wave. Highs Wednesday back into the mid 80s/dewpoints beack into 60s. Conditions will continue to become more comfortable Wednesday night and Thursday.
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&& .LONG TERM /FRIDAY THROUGH MONDAY/...
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The long term period looks fairly dry with surface high pressure dominating the weather conditions over our area. Some diurnally or terrain driven showers and thunderstorms could develop at times with shortwaves moving through, but at this moment looking at mostly dry weather conditions. Temperatures will be slightly below normal, with highs around 80 degrees, near 70 at higher elevations.
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&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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The concern is the cold front across the Ohio Valley. While the strongest activity is expected to be to our north showers and thunderstorms could reduce visibilities to IFR in heavy rainfall this evening. VFR conditions expected at all terminals after midnight through Thursday night. Mainly VFR conditions expected Friday into Sunday with high pressure building over our area.
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&& .MARINE...
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Small craft advisories in effect through 11 pm tonight. Thunderstorms are expected to be weakening tonight by the time these reach the waters but SMW wind gusts may still be possible. No marine hazards expected Wednesday through Thursday night. Wind gusts are expected to stay below the small craft advisory threshold.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ530>543. && $$ PRODUCTS...WOODY!/IMR

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