Area Forecast Discussion
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000 FXUS61 KPBZ 190927 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 527 AM EDT Wed Jul 19 2017 .SYNOPSIS... Warm and humid weather will continue for the rest of the week. Thunderstorm chances will escalate on Thursday and continue periodically into the weekend as a series of disturbances crosses the region. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... No changes were needed for the predawn update. Previous... Warmth (temperature about 5 degrees above average) and humidity (dewpoints in the upper 60s/70) can be expected again today as overall subsidence under ridging aloft is maintained between Mid Atlantic States and Great Lakes troughing. A slight chance for thunderstorms was introduced for the I 80 corridor and for the higher elevations as encroachment of a couple weak shortwaves in conjunction with possible lake breeze reinforcement and converged orographic flow may be sufficient to penetrate the mid level warmth entrenched over the Upper Allegheny region. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A more substantial shortwave is progged across the northern periphery of the Southern CONUS ridge on Thursday. That system is expected to bring the next chance for thunderstorms to all locations, and could pose a severe threat given the warmth, humidity/resultant CAPE and improved mid level flow. Models indicate a repetitive pattern for Friday and Saturday, albeit with timing and track differences, so the general chance PoPs were maintained along with ongoing warmth and humidity given those differences and boundary placement questions. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... The pattern of shortwaves crossing in zonal/northwest flow is expected to give way to Great Lakes-to-Northeastern-CONUS troughing during the first half of next week. Warmth will thus wane through the period as temperature moderates back toward, and a few degrees under the average. Likely rain chances will also diminish with dry weather projected by midweek. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... Abundant low-level moisture and clear sky/light wind will support morning/valley fog at the usual terminals (LBE/ZZV/HLG) and sporadically at MGW. This fog will lift by 13Z, with VFR conditions thereafter through the TAF period. Generally light W/NW winds can be expected. An isolated tstm is not out of the question mid-late afternoon near KFKL as a lake breeze may be sufficient to overcome the substantial mid-level inversion that will otherwise limit deep convection. Coverage/probability are low, so this potential is not included in the KFKL TAF at this time. .OUTLOOK... Broad restrictions are not expected through the remainder of the week save from morning fog and thunderstorms. In that regard, an organized convective line seems likely to affect the region Thu afternoon, leading to restrictions. Additional storms are possible through the weekend, but specific timing and geography are unclear at this time. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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