Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 24 2023 02:37:03 AWUS01 KWNH 240236 FFGMPD WVZ000-OHZ000-240835- Mesoscale Precipitation Discussion 0968 NWS Weather Prediction Center College Park MD 1035 PM EDT Wed Aug 23 2023 Areas affected...Central to Northeast OH...Northwest WV Concerning...Heavy rainfall...Flash flooding likely Valid 240235Z - 240835Z SUMMARY...Repeating rounds of very heavy showers and thunderstorms will maintain a threat for flash flooding well into the overnight hours. Some of the flash flooding is expected to be locally significant and life-threatening. DISCUSSION...The latest GOES-E IR satellite imagery shows strong MCS activity with very cold convective tops impacting much of northeast OH with multiple areas of backbuilding and locally training bands of heavy showers and thunderstorms dropping down to the south. The convection has helped to reinforce a rather strong cold pool over northeast OH, but area VWP data shows the nose of a very moist and unstable westerly low-level jet of 30+ kts interacting with the cold pool and supporting a strongly favorable environment for convection to regenerate along the lead outflow boundary and behind it in an elevated fashion atop the cold pool. MLCAPE values over western and central OH are extremely unstable with values of 3500 to 4500+ J/kg noted , and the PWs across this area are on the order of 1.75 to 2.0 inches based on 00Z RAOB data and GPS-derived PW plots. Theta-e advection associated with the low-level jet coupled with the extremely unstable environment nearby will be working tandem with a belt of stronger mid-level shear dropping south to maintain the convective threat well into the night. Proximity of a quasi-stationary front oriented close to the convective mass will also support an isentropic ascent profile that will promote convective sustenance. Recent runs of the HRRR show the convection generally advancing southward toward central OH with time, with perhaps some slight tendencies to move a bit south-southwestward going closer to the midnight time frame and beyond. Portions of northwest WV also will be likely seeing some of this activity. Overall though, the earlier HREF guidance has a rather poor handle of the ongoing activity, as the convection has been tending to show some strong backbuilding character over and near the western end of Lake Erie while also dropping farther south earlier than advertised. The Cleveland metropolitan area is already dealing with locally considerable flash flooding impacts, and the western suburbs of the city will need to closely monitor the shower and thunderstorm activity over the next few hours as backbuilding rounds of convection drop down over these areas from western Lake Erie. Expect the activity to drop eventually through central OH after midnight and areas near the Zanesville may also see a threat for locally backbuilding and training convection. Rainfall rates are expected to reach as high as 2 inches/hour, and storm totals of 3 to 5+ inches are expected locally. Additional flash flooding is likely, and some of it may be locally significant and life-threatening for the more urbanized locations. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-cp5PW6ZGbuSj1UuZpbmvb1-zpE7YPJjTmfRfHmEwDXnQBIucPUPQRlqONuQTpbtXa8C= V5DmYk94Kc_owQ7mVOOIe5Q$ for graphic product... ATTN...WFO...CLE...ILN...PBZ...RLX... ATTN...RFC...OHRFC...NWC... LAT...LON 42228283 42198184 41128138 39688068 38588055=20 38458167 38958244 39808292 41588324=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) .