Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 25 2023 04:00:24 AWUS01 KWNH 250400 FFGMPD NYZ000-PAZ000-WVZ000-OHZ000-250858- Mesoscale Precipitation Discussion 0973 NWS Weather Prediction Center College Park MD 1159 PM EDT Thu Aug 24 2023 Areas affected...Central to Northeast OH...Western PA...Western NY Concerning...Heavy rainfall...Flash flooding possible Valid 250358Z - 250858Z SUMMARY...A progressive line of heavy showers and thunderstorms will sweep across areas of central to northeast OH, western PA and western NY over the next several hours. High rainfall rates will foster concerns for some urban flash flooding. DISCUSSION...The latest GOES-E IR satellite imagery in conjunction with radar shows a progressive band of heavy showers and thunderstorms dropping east-southeast across the Lower Great Lakes region with the activity beginning to impact areas of northern OH, northwest PA and far western NY. The convection is associated with a low-amplitude shortwave impulse crossing the region along with a wave of low pressure. This energy is also interacting with the pooling of a moderate to strongly unstable airmass up across the Upper OH Valley. MLCAPE values range anywhere from 1500 to 2500 J/kg from central OH northeastward into northwest PA, with the greatest instability situated generally over central and northeast OH where the warm sector is well defined. A convergent belt of low-level west to southwest flow (30+ kts at 850 mb) is noted out ahead of the band of convection which is yielding relatively strong moisture and instability transport. This will generally maintain a favorable thermodynamic environment for convection over the next several hours as it drops through central to northeast OH, and sweeps across areas of western PA and western NY. Some moderately strong shear profiles are in place too which will also help favor convective organization in the short-term, although eventually the downstream environment which is more stable will likely drive some weakening of the activity. PWs are rather high with values near 1.75 inches and this coupled with the instability and shear should help drive rainfall rates capable of reaching 1 to 2 inches/hour despite the progressive nature of the individual convective cells. The convection will be overrunning areas of central to northeast OH, including the Cleveland metropolitan area over the next couple of hours which saw heavy rainfall and flash flooding just 24 hours ago. These areas are generally the most likely to see additional flash flooding concerns as was highlighted in MPD #972. However, the threat is a tad more uncertain over western PA and western NY where the FFGs are a bit higher. Nevertheless, the high rainfall rates will at least promote an urban flash flood threat as the heavier showers and thunderstorms arrive. This may eventually include impacts to the Pittsburgh metropolitan area in western PA and perhaps even the Jamestown area of western NY. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-amNe5RZ8suq2RXXi0ol9NQxXakazIO149yOD6WjJGE4IhvXitcdAtXCwtCfo31Nrb2b= IdmylqukuDAEk5Hyv1DwCVA$ for graphic product... ATTN...WFO...BGM...BUF...CLE...CTP...PBZ... ATTN...RFC...MARFC...NERFC...OHRFC...NWC... LAT...LON 43297847 43237734 42247719 41027818 40087991=20 40028152 40518274 41198302 41758249 42178142=20 42568003=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .