Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 19 2025 00:16:19 AWUS01 KWNH 190014 FFGMPD AZZ000-UTZ000-NVZ000-190600- Mesoscale Precipitation Discussion 0750 NWS Weather Prediction Center College Park MD 813 PM EDT Fri Jul 18 2025 Areas affected...Southern NV...Central to Southwest UT...Northwest AZ Concerning...Heavy rainfall...Flash flooding likely Valid 190013Z - 190600Z SUMMARY...Scattered clusters of heavy showers and thunderstorms will continue through the evening hours across portions of southern NV, southwest to central UT and northwest AZ. Additional localized areas of flash flooding will be likely near these storms which will include potential slot canyon, dry wash and burn scar flash flooding impacts. DISCUSSION...The late-day GOES-W visible satellite imagery along with radar data shows scattered clusters of heavy showers and thunderstorms impacting areas of southern NV through southwest to central UT and northwest AZ. The convection continues to evolve within a moist and unstable airmass characterized by SBCAPE values of 500 to 1000 J/kg, and PWs locally as high as 1.25 inches. Generally the greatest instability and moisture concentrations are over southern NV, and this is also where there is close proximity of a well-defined mid-level vort center which is drifting near the CA/NV border. A combination of this energy and the nearby lingering moisture and instability should tend to maintain a threat for heavy showers and thunderstorms going through the remainder of the evening hours. A look at the latest hires model guidance would suggest the greatest threat for this additional convection will be mainly confined to southern NV and portions of southwest to central UT. This is where radar and satellite trends show multiple outflow boundaries in close proximity to each other, which will likely tend to interact with the remaining instability in a sufficient way to facilitate additional convection over the next several hours. Outflow boundary collisions and interaction with some of the higher terrain will further enhance this threat. Rainfall rates will be capable of reaching 1.0 to 1.5 inches/hour with a lot of these rains falling in as little as 30 minutes where the stronger convective cores set up. Additional rainfall totals this evening may locally exceed 2.0 to 2.5 inches where any cells become more focused near areas of higher terrain, and especially in southwest UT. Additional areas of flash flooding appear likely based on the latest satellite and radar trends, and this will include concerns for impacts to the normally dry washes, local slot canyon areas and any burn scar locations. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4CY3AB8_SGUxProfAN5l3LjQ8ozQtjdvY3TqLcChn5klrDWKqkbRTAImWauL_owciouJ= Om7RxKdDMEPoPe_KvzDWsT0$ for graphic product... ATTN...WFO...FGZ...LKN...SLC...VEF... ATTN...RFC...RSA...STR...NWC... LAT...LON 40431231 40071089 38931093 37271195 35901192=20 35301252 35231381 36031557 37201720 38161716=20 38481604 39201417=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) .