Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 26 2025 21:31:59 AWUS01 KWNH 262131 FFGMPD AZZ000-UTZ000-NVZ000-CAZ000-270330- Mesoscale Precipitation Discussion 1141 NWS Weather Prediction Center College Park MD 530 PM EDT Fri Sep 26 2025 Areas affected...Eastern CA...Southeast NV...Southwest UT...Northwest AZ Concerning...Heavy rainfall...Flash flooding possible Valid 262130Z - 270330Z SUMMARY...Heavy showers and thunderstorms will be a threat going into the evening hours across portions of eastern CA, southeast NV, southwest UT and northwest AZ. Additional isolated to scattered areas of flash flooding will be possible. DISCUSSION...The latest GOES-W IR satellite imagery shows cold-topped convective clusters impacting northwest AZ along with southwest UT. Radar imagery shows this activity gradually beginning to cyclonically advance westward into portions of far southern NV and with some cells attempting to develop over far eastern CA. The convection across this region is largely focused within a well-defined mid-level deformation zone situated north of a closed mid to upper-level low center across eastern CA. A corridor of focused moisture convergence is seen wrapping up around the eastern and northern flanks of the closed low, and there is an axis of MLCAPE values reaching 500 to 1000 J/kg nosing up through northwest AZ and into far southeast NV. This coupled with deep layer ascent/forcing north of the closed low should help maintain a threat for convection going into the evening hours. Overall, far northwest AZ should tend to see the greatest threat over the next few hours, but areas of southern NV and eastern CA will likely see more development of showers and thunderstorms given close proximity of the closed low. This is consistent with the latest runs of the experimental WoFS guidance. The moisture environment is relatively moist with PW anomalies of 1 to 2 standard deviations above normal. This coupled with the larger scale ascent and instability should maintain convective cells capable of producing rainfall rates of 1 to 1.5 inches/hour. Additional rainfall totals locally of up to 2 inches will be possible by late this evening where some of these cells tend to be slow-moving or anchored near terrain. Additional isolated to scattered areas of flash flooding will be possible as a result going through this evening. This will include potential impacts to any burn scar locations along with the normally sensitive slot canyons and dry washes. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6A3ai2NIo4VpwyFwvySxD1vFN7nCkXNx8SpimzhhlzabtE4BIOz_C1KTNaaP9Dhprq2i= tLqM40gfidN9QyRZN_GFx2Q$ for graphic product... ATTN...WFO...FGZ...PSR...SLC...VEF... ATTN...RFC...RSA...STR...NWC... LAT...LON 37911254 37681175 36991175 36001260 35181288=20 34451317 33511359 33171437 33251529 33811597=20 34971616 35791604 36511573 37231505 37741396=20 =20=20=20=20=20=20=20=20=20=20=20=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) .