Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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846 FXUS61 KPBZ 052153 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 553 PM EDT Fri Jul 5 2024 .SYNOPSIS... Shortwave passage will create periods of moderate rain showers with low probability thunder through tonight, along with a non zero damaging wind and flood threat. Dry weather returns Saturday through Monday with temperature rising well above normal by Monday afternoon. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... KEY MESSAGES: - Shower and thunderstorm activity will become more widespread tonight, with a still-present risk of localized flash flooding. The risk of damaging wind gusts remains low. ------------------------------------------------------------------- Only a few light rain showers are in progress across the forecast area currently. SPC mesoanalysis and ACARS soundings have shown little in the way of MLCAPE over the past few hours, with a large portion of the area having 500 J/kg or less, along with capping at around 800mb or so. This has prevented much of any development to this point, let alone any severe weather chances. Have reduced PoPs for the next couple of hours as a result. A cluster of showers and thunderstorms has formed further down the Ohio River in the RLX CWA, where some low- level convergence and more favorable instability have fueled thunderstorms producing heavy rainfall totals. A shortwave is still progged to move through between 00Z and 06Z, which may yield a greater uptick of storm development across western PA but with low probability of severe weather. Flash flooding will remain possible as high PWAT persist, but strong enough steering flow and relatively dry antecedent conditions should keep risk low. Expect that the current downriver activity will fade somewhat over the next couple of hoers as it lifts northeast into a more hostile convective environment, but a threat of localized downpours will persist. Passage of a surface trough and upper wave will diminish precipitation chances west to east and offer a slight reprieve from the warm, muggy conditions. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... KEY MESSAGES: - Dry and more seasonable weather returns on Saturday. - Rising temperature likely through Monday as dry weather persists. ------------------------------------------------------------------- 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. Return flow as high pressure settles over the Atlantic will support rising temperature Sunday into Monday as the next upper trough system develops over the Central Plains. Heat risk concerns return as a result, though probabilities of seeing heat indices above advisory criteria remain low. && .LONG TERM /TUESDAY THROUGH FRIDAY/... 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. ------------------------------------------------------------------- Ensemble consensus continues to favor an Upper Midwest trough lifting through the Great Lakes region Tuesday into Wednesday morning with a weak surface trough. Moist advection ahead of the wave is likely to foster a warm, humid environment translating to likely showers and thunderstorms ahead of the feature. Environmental conditions remain varied, but with ensemble means showing near 90F highs and 70F dewpoints, there appears to be at least a low probability for flash flood risk and potential other severe hazards. Variations become post-shortwave passage depending on high pressure strength to the north as well as potential pattern impact from the remnants of Hurricane Beryl. The main takeaways for the long range period is that 500mb mean heights suggest a continuation of near to above normal temperature and precipitation chances tied to shortwave movement. && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/... 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...Frazier NEAR TERM...Frazier/CL SHORT TERM...Frazier LONG TERM...Frazier AVIATION...88