Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 20 2025 02:06:45 AWUS01 KWNH 200206 FFGMPD INZ000-ILZ000-MOZ000-200705- Mesoscale Precipitation Discussion 0293 NWS Weather Prediction Center College Park MD 1005 PM EDT Mon May 19 2025 Areas affected...Central and Southern MO...Central and Southern IL Concerning...Heavy rainfall...Flash flooding likely Valid 200205Z - 200705Z SUMMARY...Increasing coverage of showers and thunderstorms with high rainfall rates along with areas of cell-training will likely result in scattered to numerous areas of flash flooding overnight. Locally significant and life-threatening urban flash flooding impacts will be possible. DISCUSSION...A well-organized band of heavy showers and thunderstorms with very cold convective tops continues to generally expand in coverage across central and southern MO with additional cells seen in radar imagery beginning to develop also farther east across eastern MO and small portions of western IL. All of this continues to evolve as a very strong warm-air advection pattern advances across the middle MS Valley and into the lower OH Valley with enhanced moisture and instability transport seen focusing up along and over a warm front. MLCAPE values are as high as 2000 to 3000 J/kg from central and southern MO through southern IL involving the warm sector, and the environment is very moist and strongly sheared with PWs of 1.6 to 1.8+ inches and effective bulk shear values of 50+ kts. As a result, the convective mode is inclusive of supercell thunderstorms, and the latest radar shows a number of embedded supercells within the broader axis of convection. Over the next several hours, areas of significant cell-training will be a concern across areas of southern and eastern MO and into southern IL where radar trends along with recent hires model guidance supports the convection becoming increasingly aligned with the deeper layer southwesterly flow across the region. The latest HRRR, RRFS and experimental WoFS guidance all support high rainfall rate potential with the evolution of the supercell thunderstorm activity over the next few hours with rainfall rates reaching as high as 2.5 inches/hour, and this is certainly supported by the highly favorable thermodynamic and kinematic environment that is in place. Cell-training will likely favor some storm totals of 3 to 5 inches with isolated heavier totals to 6+ inches possible. This will likely result in scattered to numerous areas of flash flooding which will include the potential for significant and life-threatening urban flash flooding impacts. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!66kuZVZ6W0BjlOXg3oPFMYzM38EtDM2KnSaaV6CzYZ3fWpFETgG2mSJduUdnVmA4_ezm= 7hcNUjDEnTNXU3BgWBAF1DU$ for graphic product... ATTN...WFO...ILX...LSX...PAH...SGF... ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC... LAT...LON 40338905 39488773 37988803 36669033 36519312=20 37399357 39109227 40159086=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) .