Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 09 2025 23:30:05 AWUS01 KWNH 092330 FFGMPD MOZ000-IAZ000-KSZ000-NEZ000-COZ000-100525- Mesoscale Precipitation Discussion 0887 NWS Weather Prediction Center College Park MD 727 PM EDT Sat Aug 09 2025 Areas affected...Eastern CO...Much of Northern KS...Southern NE Concerning...Heavy rainfall...Flash flooding possible Valid 092327Z - 100525Z SUMMARY...Increasing coverage of supercell thunderstorms with gradual consolidation into an MCS is generally expected this evening. Locally high rainfall rates and cell-merger activity will pose at least an isolated threat for flash flooding. DISCUSSION...The late-afternoon GOES-W visible satellite imagery along with radar shows multiple supercell thunderstorm clusters organizing and generally expanding in coverage across portions of eastern CO. This activity will be gradually advancing off to the east this evening into a strongly unstable airmass pooled along and north of a stationary front, with MLCAPE values currently on the order of 2000 to 4000 J/kg. The environment is strongly sheared and conducive for additional supercell thunderstorm development which will gradually set the stage for cell-mergers and consolidation of activity into a larger scale MCS later this evening. Additional factors supporting convective expansion is arrival of stronger upper-level jet support/forcing from the central Rockies out ahead of a digging upper-level trough over the Intermountain West. A gradual increase in a southerly low-level jet is also forecast this evening across the central Plains which will further aid ascent across the High Plains in close proximity to the aforementioned frontal zone. In fact, the latest HRRR guidance supports a 40+ kt low-level jet nosing up across northern KS by late this evening and this will likely support a more organized level of convection advancing east from eastern CO and into areas of northern KS and southern NE, which may include downstream development ahead of the eastern CO MCS evolution. Rainfall rates with the stronger supercells and with any cell-merger activity may reach 2 inches/hour, and the increase in moisture transport later this evening will encourage these higher rates. Some localized storm total amounts going through midnight may reach 3 to 4+ inches. The antecedent conditions for most of the region is on the dry side, but the cell-merger activity and resultant rainfall totals may foster some isolated flash flooding concerns. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6nAZzP8RQyE2TSvJixwe3jsJaDy_qDZyIA-f4vq5EdyRvFF57gTKgae_Pli53uy9J03i= o3hqrJvTg2b3OwZPU8bhLcI$ for graphic product... ATTN...WFO...BOU...DDC...EAX...GID...GLD...ICT...LBF...OAX... PUB...TOP... ATTN...RFC...KRF...TUA...NWC... LAT...LON 41419772 41299637 40429550 39209582 38749823=20 38469961 37980172 38120289 38740389 39960404=20 40690258 40970116 41199961=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) .