Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 17 2025 03:18:24 AWUS01 KWNH 170316 FFGMPD VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-MOZ000-ARZ000-170915- Mesoscale Precipitation Discussion 0281 NWS Weather Prediction Center College Park MD 1115 PM EDT Fri May 16 2025 Areas affected...Portions of the OH/TN Valleys Concerning...Heavy rainfall...Flash flooding possible Valid 170315Z - 170915Z SUMMARY...Strong to severe thunderstorms will continue into the overnight hours across portions of the OH/TN Valleys, and will be capable of also producing heavy rainfall totals. A combination of cell-mergers and cell-training with moist antecedent conditions will maintain a threat for scattered areas of flash flooding. DISCUSSION...A well-organized severe weather outbreak continues to unfold across areas of southern OH down through especially central to southwest KY and northwest TN as a deep layer closed low advances east across the upper Midwest and sends a cold front southeastward into a very moist and unstable airmass. MLCAPE values this evening remain locally quite high across especially central KY through western TN with values of 2000 to 3000 J/kg in place. This strong instability continues to work in tandem with enhanced shear profiles with 50 to 70+ kts of effective bulk shear to support supercell convection with an evolution into multiple linear bands/QLCS of activity over the next several hours as the broader convective threat advances eastward. The onset of nocturnal cooling will be initiating a gradual stabilization of the boundary layer and thus introducing some low-level CINH, but the hires model guidance suggests some intensification of the southwest low-level jet to as much as 50+ kts by 06Z. This should maintain a strong degree of moisture and instability transport up across especially central and northern TN through central and eastern KY that will be conducive for maintaining a corridor of well-organized convection with heavy rainfall rates. Rainfall rates with the stronger and more organized cells will be capable of reaching 2 inches/hour, and with some likelihood for seeing cell-merger activity and cell-training, some additional rainfall totals of 2 to 4 inches will be possible. This is consistent with the 00Z HREF guidance, and it should be noted that recent HRRR runs overall appear to be locally a bit underdone with its QPF potential considering the high rainfall rates and cell-training concerns. The antecedent conditions across much of the region are quite moist, and some areas saw heavy rainfall just within the last 12 to 18 hours. As a result, the additional rainfall amounts may result in scattered areas of flash flooding overnight. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6PWZMbL2SI6-aVebvdYnKT9Bm1kg1Wi4pF_DChZcHM7ZcaMU4nlY3I25chwg2XN5i0H4= _WPFeVs7jaH2vQ9BxK1ri8o$ for graphic product... ATTN...WFO...ILN...JKL...LMK...MEG...MRX...OHX...PAH...PBZ... RLX...RNK... ATTN...RFC...LMRFC...OHRFC...NWC... LAT...LON 39848076 38698000 37528106 36408303 35738505=20 35418803 35718965 36508976 37168760 37818589=20 38548465 39618286=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .