Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 08 2024 22:12:06 AWUS01 KWNH 082212 FFGMPD AZZ000-NVZ000-CAZ000-090310- Mesoscale Precipitation Discussion 0985 NWS Weather Prediction Center College Park MD 610 PM EDT Sun Sep 08 2024 Areas affected...Southern CA into Far Southern NV and Northwest AZ Concerning...Heavy rainfall...Flash flooding possible Valid 082210Z - 090310Z SUMMARY...A threat for isolated to widely scattered instances of flash flooding will continue into the early evening hours from areas of locally heavy showers and thunderstorms. DISCUSSION...The mid-afternoon GOES-W visible satellite imagery shows scattered areas of showers and thunderstorms across portions of the higher terrain of southern CA and locally across some of the open desert areas of eastern CA and far southern NV. Some areas of showers and thunderstorms have also been seen developing over northwest AZ. The convection is generally associated with the strong diurnal heating cycle coupled with terrain-driven differential heating boundaries/circulations and the presence of at least a modest amount of moisture through the vertical column. SBCAPE values of 1000 to 1500 J/kg are noted locally across areas of southern CA through southern NV. The better moisture is generally in the mid-levels of the column (500 to 700 mb layer) based off the latest CIRA-ALPW data, but this is still facilitating cold-convective tops and locally heavy rainfall rates based on the latest satellite trends. Ongoing areas of locally heavy showers and thunderstorms may tend to further expand in coverage over the next 2 to 3 hours before the activity then begins to wane as surface-based instability gradually becomes exhausted. The PWs are seasonably moist across the region, and coupled with the instability, this should favor convection over the next few hours that will still be capable of producing rainfall rates of 1 to 1.5 inches/hour. Some spotty storm total amounts of 2 to 3 inches will be possible where any cells become locally anchored over the high terrain, and some of these slow-moving cells have already occurred over the higher terrain of southern CA. These rainfall amounts may result in additional concerns for isolated to widely scattered instances of flash flooding going into the early evening hours. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!70WNzAzxHUt_pCRJIj9YSaKX45qOdTze0KcbEPBhWr7f9Tbeg08KcQZ4t3jkRjxQ-qGh= EWvoI2Fon1jGBkqG25bFz5g$ for graphic product... ATTN...WFO...FGZ...HNX...LOX...PSR...SGX...VEF... ATTN...RFC...CBRFC...CNRFC...NWC... LAT...LON 36891476 36871327 36311233 35111156 34311185=20 34331279 34741412 34631558 34311610 33941654=20 33641657 33261652 32641639 32481684 32971706=20 33501734 34001771 34291819 34691839 35141827=20 35601775 35771712 36051649 36541575=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) .