Area Forecast Discussion
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398 FXUS61 KPBZ 220935 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 535 AM EDT Tue Aug 22 2017 .SYNOPSIS... Showers and thunderstorms are expected this afternoon and evening with the approach and passage of a cold front. Some storms could be severe. Mainly dry and cooler than average weather is expected the rest of the week under high pressure. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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No major changes for the pre dawn update. Hi res models show current showers/storms across IN weakening and tracking N of the area this morning. This is supported by meso analysis precip propagation vectors and warming cloud tops on satellite. Previous...Strong low pressure is progged to track across the Upper Great Lakes to Ontario today, pulling a cold front toward the region. Showers and thunderstorms are expected to develop by this afternoon along a pre frontal trough. Model progged wind profiles, increasing shear values, and building daytime instability continue to look favorable for severe thunderstorms with the approach and passage of the pre frontal trough. SPC`s slight risk/sct coverage outlook for most of the area still seems reasonable. An enhanced, more numerous coverage area was included toward nrn PA where slightly higher shear values are progged. Damaging wind still appears to be the primary threat, though an isolated occurrence across the severe weather spectrum will be possible. Rapid storm motion should preclude a widespread flash flood potential. Synoptic winds outside of any thunderstorms are also expected to increase this aftn with a tightening pressure gradient and mixing, with SW gusts to around 30 mph expected. Highs are expected to be several degrees above seasonal levels.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/... The severe weather potential is expected to end with the passage of the pre frontal trough by early evening, though with cold frontal passage progged later in the evening/overnight, shower/thunderstorm chances will continue until FROPA. Otherwise, surface high pressure building under ern CONUS upper troughing should maintain dry and cooler than average weather for the rest of the period. && .LONG TERM /FRIDAY THROUGH MONDAY/... Broad surface high pressure under NE CONUS upper troughing should maintain the dry and cooler than average weather through the period. && .AVIATION /10Z TUESDAY THROUGH SATURDAY/... Mainly high clouds overnight. Fog does not appear to be much of a threat given the warm overnight temperatures which will not allow crossover values to be reached. As a cold front approaches today, showers and thunderstorms will become more numerous this afternoon and evening. Flight condition deterioration with VCTS and a drop to MVFR visibilities at several terminals during the late afternoon. Expect prevailing winds outside of convection to increase to gust to between 15 and 25 knots out of the southwest during the afternoon. .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. && $$ 07/22

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