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683 FXUS61 KPBZ 211104 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 704 AM EDT Mon Aug 21 2017 .SYNOPSIS... A weak upper level trough has returned low rain chances to the forecast today. Widespread showers and thunderstorms are expected with the approach and passage of a Tuesday cold front. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... The dawn update included some adjustments to POPs in the form of a slight convection chance with the shortwave emerging from the midwest. High res models do indicate ongoing showers over Ohio will fade, but cannot rule out an isolated occurrence with the advance/passage of that system, especially with the increasing warmth and humidity in the boundary layer. Otherwise, an increase in mid and high level cloudiness is likely to mar the eclipse viewing, although a brief period of shortwave ridging may save the "peak" time of the event. High temperature is expected to be around 5 degrees above the seasonal average. && .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 /12Z MONDAY THROUGH FRIDAY/... General VFR is expected for the period although a crossing shortwave may spawn some isold, to sct convection. Expect rapid deterioration of conditions on Tuesday as widespread precip will herald the advance of cold front. .Outlook... With passage of an early Wed cold front, general VFR can be expected for the remainder of the week. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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