Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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309 FXUS61 KPBZ 051712 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 112 PM EDT Fri Jul 5 2024 .SYNOPSIS... Shortwave passage may generate afternoon and evening convection with a low probability threat for damaging wind and localized flash flooding. Dry weather and rising temperature is expected through Monday before the next disturbances approaches mid week. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - A conditional threat exists for damaging wind and localized flash flooding this afternoon and evening. - Uncertainty exists in convective and instability development to create hazard risk. ------------------------------------------------------------------- A weak shortwave and surface trough are expected to lift northeast through the Ohio River Valley through tonight, though the trough axis may linger southeast of the region into Saturday. Satellite and radar imagery show ongoing convection entering SW Ohio where surface and elevated instability becomes more limited. This highlights a growing conditional issue for thunderstorms and severe weather today: both the 12z sounding at KPIT and KILN show notable warm air aloft that is capping available instability. Given area cloud cover and increasing mid to high-level clouds moving NE off the decay convection, there is greater uncertainty that storms will maintain and/or develop as the shortwave regions this region as heating/destabilization may not be realized until late this evening when forcing better maximizes over the area. That said, there remains a threat for hazardous weather (in the form of damaging wind and localized) due to the elevated PWAT values, increasing shear, potential for 1000-1500 SBCAPE, and presence of some drier air aloft. It would remain conditional on storm formation and instability maximization (which is likely needed to overcome poor lapse rates), with current analysis suggesting locations south of I-70 having the greatest potential. The shortwave will more notably pass between 00z-06z, which may yield a greater uptick of storm development across western PA but with a lower probabilistic severe environment. Passage of the surface trough and upper wave will diminish precipitation chances west to east and offer a slight reprieve from the warm, muggy conditions. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... KEY MESSAGES: - Dry and more seasonable weather returns on Saturday. ------------------------------------------------------------------- Drier southwest flow and ridging at the surface will support dry weather Saturday. Lingering morning stratus clouds are expected to break up with a scattered to broken cumulus field developing in the late morning to early afternoon; weak cool advection plus the cloud cover should aid temperature returning to more seasonal values. More notably for some, drier air will mix to the surface and bring relief to the region from the multiple day experience of humid conditions. && .LONG TERM /SUNDAY THROUGH THURSDAY/... KEY MESSAGES: - High probability for dry weather and slightly above average temperature the rest of the weekend. - Unsettled weather returns Tuesday through at least mid-week. ------------------------------------------------------------------- Confidence remains high in dry weather continuing into the new week as surface ridging remains over the Ohio Valley and upper troughing persists over the Central Plains. Temperatures should remain near-normal on Sunday, but increasing return flow and warm advection on Monday ahead of the next low pressure system will drive daily highs back above-normal. Ensembles indicate more active weather Tuesday into Wednesday as low pressure crosses and upper troughing sets up across the East. High pressure will return for Thursday with most activity being a slight chance or less but most likely dry. && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... Scattered showers and thunderstorms will be possible late afternoon / evening with a shortwave and ahead of a crossing front. Have used a PROB30 for KMGW, but removed mention elsewhere with low confidence in timing or location. Cigs should lower into MVFR/IFR again overnight with lingering moisture, eventually lifting Saturday morning as drier air moves in behind the front. .Outlook... VFR conditions should persist through the weekend with high pressure. The next chance for widespread restrictions will be with our next system Tuesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Shallenberger NEAR TERM...Frazier SHORT TERM...Frazier LONG TERM...Frazier AVIATION...88