Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 06 2025 23:25:36 AWUS01 KWNH 062325 FFGMPD AZZ000-NVZ000-CAZ000-070500- Mesoscale Precipitation Discussion 0237 NWS Weather Prediction Center College Park MD 724 PM EDT Tue May 06 2025 Areas affected...eastern CA, southern NV, western AZ Concerning...Heavy rainfall...Flash flooding possible Valid 062323Z - 070500Z SUMMARY...An increasing coverage of thunderstorms across portions of eastern CA, southern NV and western AZ over the next 2-4 hours will be capable of flash flooding. Rainfall of 0.25 to 0.50 inches in 15 minutes and storm totals of 1-2 inches are expected on a spotty basis. DISCUSSION...GOES West water vapor imagery placed a closed mid-level low over south-central NV at 23Z, advancing slowly to the south. The approach of this low and its southern elongation into CA has allowed low level winds to shift from a northerly direction this morning to southwesterly to its south, increasing low level theta-e values into the lower Colorado River Valley. The combination of surface heating and low level moisture advection has increased MLCAPE values into the 500-1000 J/kg range from southern NV into eastern CA and western AZ via the 23Z SPC mesoanalysis. Visible satellite and radar imagery showed a few thunderstorms along the NV/AZ border, co-located with severe and flash flood warnings. Visible satellite imagery also showed developing cumulus over eastern CA with a few early thunderstorms over the Mojave Desert. Continued low level moisture advection into eastern CA and western AZ is expected to allow for marginal increases in an already highly anomalous moisture axis (standardized PW anomalies of +3 to +4). Mean westerly deeper layer flow of roughly 10 kt from the west will be co-located with similarly oriented and slightly stronger 700 mb winds which will be likely to support repeating cells and brief upwind propagation of cells. Rainfall rates within this environment should be easily capable of producing 0.25 to 0.50 inches of rain in 15 minutes or less, which could result in some flash flooding of low lying areas and normally dry washes. Storm total rainfall of 1 to 2 inches is expected through 05Z. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_vfrOuTSTuZgQ-GHE-ivVTl3OphkUUwxyfxnNfyUUGizRv3bkOVdE4RQ_dz8I94WsHce= E2p9xS2vDy1dJ_bBFPPiV5I$ for graphic product... ATTN...WFO...FGZ...PSR...VEF... ATTN...RFC...CBRFC...CNRFC...NWC... LAT...LON 36511331 36321268 35751210 35141165 34561186=20 33541272 33011382 33031480 33761571 34501618=20 35261582 35671479 36481378=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .