Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 28 2025 00:26:42 AWUS01 KWNH 280026 FFGMPD KSZ000-COZ000-280530- Mesoscale Precipitation Discussion 1016 NWS Weather Prediction Center College Park MD 825 PM EDT Wed Aug 27 2025 Areas affected...Eastern Colorado...Western Kansas... Concerning...Heavy rainfall...Flash flooding possible Valid 280030Z - 280530Z SUMMARY...Increasing convection at near strengthening surface low may result in slow moving clusters with eventual upstream mergers before main WAA/isentropic ascent/training event occurs downstream. Localized 2-4" totals through 04-05z may result in possible localized flash flooding incidents.=20 DISCUSSION...Larger, synoptic scale trough over ID/MT Rockies continues to elongate into a string of vorticity centers along the northern edge of the synoptic ridging centered over the New Mexico and Colorado High Plains. The eastward edge of the vorticity strip has fostered strong convective cells, expanding into a forward propagating line of cells across W NEB into NE CO which will continue to march southward intersecting return low level moisture and upslope flow over E CO/NW KS over the next few hours. The DPVA along with strong right entrance of exiting northwesterly upper-level jet over central and eastern KS; as well as nose of approaching speed max out of the Four Corners is supporting solid divergent pattern over eastern CO to support the thunderstorm activity, but more importantly continue to deepen the surface cyclone south of Burlington, CO. A well defined surface front is bending under the deepening low's influence as well as increasing deep layer moisture convergence along/ahead of the advancing convective line with newer downstream cells starting to break out over W KS. These clusters will continue to strength/expand and with increasing deep layer moisture inflow will increase in rainfall efficiency over the next few hours over far E CO. Sub-hourly/instantaneous rates will be strong but forward propagation may only support localized 1.5-2" totals. However, pre-convective line cells developing in proximity to the surface low and southward trending pressure trof/convergence axis seen very well in late-day visible imagery have been developing slow moving thunderstorms with solid 20kt surface to boundary layer inflow of mid 60s Tds and are supporting 1.5-2"/hr rates.=20 Slow motions, waiting for the upstream DPVA/height-falls have been allowing some localized totals nearing 2-3" and may continue to support other local totals up to 4" before the main line arrives.=20 While much of SW KS has the locally higher FFG values, a few spots may be exceeded and result in a localized/focused incident or two of flash flooding. Eventually, as the boundary layer decouples after sunset and the LLJ starts to strengthen and broaden, isentropic ascent along the frontal zone ahead of the approaching convective line will develop and orient generally parallel to the mean steering flow allowing for training and eventual more likely flash flooding concerns later overnight into central KS (and downstream), but a subsequent MPD will be written close to that time frame, but until that time...scattered flash flooding remains locally possible. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9bE754lxoKw5PZsgItqw74IudG_FzFFHd9AjW4SzoVEeD2nJei7ET2paaCwiQHxiPcxx= SlgCy-euS1E0W2i9zW8vd1k$ for graphic product... ATTN...WFO...BOU...DDC...GLD...PUB... ATTN...RFC...KRF...TUA...NWC... LAT...LON 40140258 39810163 39209996 38769930 38379909=20 37699933 37370015 37180122 37380175 37910231=20 38210263 38560311 39030358 40090333=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) .