Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Sep 22 2025 23:14:48 AWUS01 KWNH 222314 FFGMPD KSZ000-COZ000-230500- Mesoscale Precipitation Discussion 1118 NWS Weather Prediction Center College Park MD 713 PM EDT Mon Sep 22 2025 Areas affected...Portions of Far Eastern CO and Western KS Concerning...Heavy rainfall...Flash flooding possible Valid 222313Z - 230500Z SUMMARY...Developing and expanding clusters of heavy showers and thunderstorms are expected going into the evening hours across portions of far eastern CO and western KS. Isolated areas of flash flooding will be possible. DISCUSSION...Late-day GOES-E visible satellite imagery along with regional radar data shows developing and gradually expanding clusters of heavy showers and thunderstorms across parts of far eastern CO and northwest KS, with the activity focusing along a developing frontal boundary. Increasing low-level moisture convergence is noted along this front, and the convection is developing within a moderate to strongly unstable airmass characterized by MLCAPE values of 1500 to 2500 J/kg. This instability along with 30 to 40+ kts of effective bulk shear is already favoring some supercell thunderstorm development, and over the next several hours as upstream shortwave energy/forcing arrives from central Rockies and crosses the High Plains, there will be a favorable environment for expanding and organizing clusters of multicell and supercell thunderstorms. By early to mid-evening, the main convective threat area should involve far eastern CO and western KS, but a combination of cell-merger activity and upscale MCS development is expected in time as DPVA/height falls provide stronger forcing in conjunction with a strengthening southerly low-level jet across the central Plains ahead of the aforementioned front. This will gradually allow for the convective mass to expand off to the east and southeast going through the overnight hours. While much of the convection this evening will primarily be of a severe nature, there will be sufficient levels of moisture transport and convective cell organization to promote high rainfall rates that may reach 1 to 2 inches/hour. Cell-merger activity and localized cell-training concerns may foster there being some rainfall totals of 3 to 4+ inches by mid-evening. This is consistent with the 18Z HREF/12Z REFS suites of guidance. As a result, there may be an isolated threat for some flash flooding over the next several hours as these stronger multicell and supercell thunderstorm clusters evolve. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9IJ6lg5u3UtcfLHVvR4vbV7rFLaQCb6tyJnIuXhtyRieIFnzk0e7ShbKimi-k8gEWlIH= KCoQQcTf82-USiTV5IvTXQc$ for graphic product... ATTN...WFO...BOU...DDC...GID...GLD...PUB... ATTN...RFC...KRF...TUA...NWC... LAT...LON 39710138 39670031 39479958 38769927 38109956=20 37950065 38300152 38400196 38680289 38800343=20 39250362 39500322 39620231=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .