Area Forecast Discussion
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232 FXUS61 KPBZ 210940 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 540 AM EDT Mon Aug 21 2017 .SYNOPSIS...
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A weak upper level trough will return low rain chances to the forecast today. Widespread showers and thunderstorms are expected with the approach and passage of a cold front Tuesday and Tuesday night.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A weak shortwave trough advancing out of the Midwest should result in slight shower chances mainly N of PIT early this morning, though weak forcing a lack of deep layer moisture should limit this potential. A period of weak shortwave ridging is expected after the wave exits by early afternoon, though mid/high clouds from a weakening Midwestern MCS could at least somewhat mar eclipse viewing. Isolated thunderstorms are possible by late afternoon as the ridging flattens and convective temps are reached. Temperatures are expected to be around 5 degrees above the seasonal average.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Isolated thunderstorms are possible this evening, though these should diminish with waning instability after sunset. By Tuesday, strong low pressure is forecast to track across the Great Lakes, pulling a cold front toward the Ohio Valley. Showers and thunderstorms are expected as the front approaches, and as a pre frontal trough tracks across the area. Model progged wind/shear profiles look favorable for a damaging wind potential with the storms, though warm mid levels could initially limit instability. SPC`s slight risk/sct coverage outlook for severe storms seems reasonable at this time, and will continue to include in the Hazardous Weather Outlook. Outside of any storms, a tightening pressure gradient and mixing could result in 25-30 mph wind gusts. The pre frontal trough passage is timed to end the severe threat by Tuesday eve, with early Wednesday frontal passage heralding cooler temperatures. Building sfc high pressure under broad should maintain the dry and cool weather Wed night. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Broad surface high pressure under Eastern CONUS troughing is progged to support dry and cooler than average weather through the period. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... High pressure will provide prevailing VFR conditions through the period. A brief period of pre-dawn MVFR fog is possible at southern ports. .Outlook... Widespread restriction potential returns with a late Tue/early Wed cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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