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Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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614 FXUS61 KPBZ 050600 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 200 AM EDT Fri Jul 5 2024 .SYNOPSIS... A series of disturbances will create periods of scattered thunderstorms through Friday, offering low probabilities for localized flash flooding and gusty wind. Dry weather with seasonable temperature will return Saturday into Sunday. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... KEY MESSAGES: - Scattered showers and thunderstorms early this evening will become more numerous - Locally heavy rainfall possible where training occurs ------------------------------------------------------------------- One shortwave/vorticity maximum continues to track across western PA, with a remnant MCV east of PIT. This will exit the region this evening. Another shortwave/vorticity maximum was crossing western Ohio, with additional showers and thunderstorms ahead of it. The next wave should cross the area this evening/overnight, with showers and thunderstorms becoming more numerous. The 00Z PIT sounding shows precipitable water at 2.13 inches, with ML CAPE near 1000 j/kg. Mid level lapse rates are weak with warm air aloft. This is likely the limiting factor on stronger storms this evening. The latest mesoanalysis shows an overall decrease in CAPE values over the last three hours. Shear has increased to near 40kt, though with the weak mid level lapse rates most of the storms have not been able to strengthen. The main concern remains localized flooding where training of thunderstorms occurs. The severe weather potential should gradually wane overnight, with the localized flood potential likely continuing until shortly after midnight. Showers and thunderstorms should taper off from west to east later tonight as the shortwave exits. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... KEY MESSAGES: - More widespread coverage is expected Friday, with damaging wind and flash flood threats remaining possible. - Dry and more seasonable weather returns on Saturday. ------------------------------------------------------------------- A more organized shortwave and surface low pressure crossing the Great Lakes will lift the stationary boundary northward as a warm front and push a late-day cold front through the region. Breaks in cloud coverage and weak cooling aloft should help destabilize the otherwise unchanged environment (modest CAPE, moderate shear, weak lapse rates, high PWAT values). The expectation is for greater shower and thunderstorm coverage during the afternoon and evening Friday ahead of each boundary, with damaging wind and localized flash flooding threats possible. Improved forcing and instability should be negated by stronger storm flow to leave the overall flash flood threat similar to that seen today. Passage of the surface cold front and upper shortwave will diminish storm chances Friday night, with dry and seasonable weather returning on Saturday. && .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 through the weekend 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 mid-week as low pressure crosses and upper troughing sets up across the East. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Line of showers and a few embedded thunderstorms continues to cross the area early this morning. Brief vsby restrictions have generally dropped to 2SM as these roll over terminals. IFR cigs are expected to overspread the area from west to east in the next several hours, eventually lifting back to VFR by late morning. An additional round of showers and thunderstorms with occasional restrictions is expected Friday afternoon and evening with a more robust shortwave and in advance of a crossing cold front. Storms look to remain scattered/isolated, with some uncertainty on exact timing at specific locations. Have continued to use PROB30s for this threat. Cigs should lower into MVFR/IFR again Friday night with lingering moisture, eventually lifting Saturday morning. .Outlook... VFR conditions should persist through the weekend with high pressure. The next chance for widespread restrictions will be with our next system Monday into Tuesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Frazier NEAR TERM...WM SHORT TERM...Frazier LONG TERM...Frazier AVIATION...Rackley