Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 27 2025 00:17:57 AWUS01 KWNH 270017 FFGMPD NVZ000-CAZ000-270600- Mesoscale Precipitation Discussion 1013 NWS Weather Prediction Center College Park MD 817 PM EDT Tue Aug 26 2025 Areas affected...Southern Nevada...Far Southeast California Deserts... Concerning...Heavy rainfall...Flash flooding possible Valid 270015Z - 270600Z SUMMARY...Converging clusters in vicinity of remaining unstable, moist air mass to continue widely scattered incidents of localized flash flooding through early overnight period. DISCUSSION...GOES-W WV suite continues to show main larger scale cyclone exiting the northern Great Basin toward the Snake River Plain with active clusters of activity along the far western peripheries across the terrain of the Sierra Nevada and in proximity to the San Bernandino Ranges. These clusters are expected to continue through northwesterly flow and generally merge across the southern Great Basin. Currently, there remain stronger thunderstorms across central San Bernandino county lifting northward feeding on the remaining limited unstable air at the northwestern edge of deeper lingering moisture (1-1.25" total PWats) through the higher deserts of southeast CA. Cells appear to have generated a cold pool resulting in northeasterly proapgation and are exepected to diminsh in the next few hours.=20 Still, cells remain capable of a quick .5" of rain in less than 30-60 minutes and given desert, hard rock conditions; flash flooding would remain possible though increasingly more scattered in nature with time. However, this cluster's outflow will remain important as it slides northeast into SW NV as it will intersect with outflow/convergent band at nose of northwesterly flow/downward mixing eminating from the central Sierra Nevada Range. Combine that with return moisture flow from south to southeasterly flow out of the Colorado River Valley, much of southern and central Nevada remain conditionally unstable with 1000-1500 J/kg of MLCAPE analyzed by the RAP. Total moisture also remains above normal with 1.25"+ Total PWats. As the boundaries intersect toward sunset, an uptick in convective coverage and intensity is expected. Cell motions are likely to limit overall totals, but 1-1.5"/hr rates and localized totals of 1" over desert/rocky ground conditions (where FFG values are generally less than .75") suggests a few widely scattered, locally focused instances of flash flooding will remian possible through 06z.=20=20 Of note, GOES-W Visible imagery shows a bit of mixed aerosols (mainly smoke over the central Great Basin (NW Nye county and northwest), cells that have been ingesting the aerosols have shown a slight increase in rainfall efficiency given increased nucliation resulting in small but more numerous rain droplets effectively acting like more tropical/warm cloud processes. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!74V1dPr2V1I7qJf3U3tYiCzCXFm_qRKibEVubKecco-jKljHyi40E6AStWz4aXw7Ht9p= V_ww2Bc9suShVQLNSbhwmIY$ for graphic product... ATTN...WFO...LKN...REV...VEF... ATTN...RFC...RSA...STR...NWC... LAT...LON 40251764 40111691 39701583 39361516 38951453=20 38251419 37241426 36291485 35281569 34911637=20 34931728 35371759 35911762 36431763 37861786=20 38501830 39141857 39681846 40111816=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) .