Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 19 2025 18:02:46 AWUS01 KWNH 191802 FFGMPD TXZ000-NMZ000-AZZ000-UTZ000-NVZ000-CAZ000-200000- Mesoscale Precipitation Discussion 1108 NWS Weather Prediction Center College Park MD 200 PM EDT Fri Sep 19 2025 Areas affected...Far Eastern CA...Far Southeast NV...Northern and Eastern AZ...Western and Central NM Concerning...Heavy rainfall...Flash flooding possible Valid 191800Z - 200000Z SUMMARY...A gradual increase in heavy shower and thunderstorm activity is expected going through the afternoon hours which will bring a concern for mainly isolated areas of flash flooding. This will include potential impacts to dry washes and burn scar locations. DISCUSSION...The GOES-E WV suite shows mid-level shortwave energy gradually ejecting off to the east across northern and eastern AZ and into western NM which should interact with the diurnal heating cycle today to yield scattered areas of heavy showers and thunderstorms. SBCAPE values are locally already upwards of 1000 to 2000 J/kg across southeast AZ, with adjacent areas of western NM also destabilizing rather rapidly due to strong diurnal heating. In fact, the latest visible satellite images are showing an increasingly agitated CU field beginning to take shape across these areas, and convective initiation will likely be taking place within the next hour or two near areas of higher terrain which is also suggested by the latest AI-based LightningCast output. PWs across the region remain anomalously high with values 1.5 to 2.5 standard deviations above normal across southern AZ into western NM, and this coupled with the increasing boundary layer instability will favor heavy showers and thunderstorms with rates as high as 1 to 2 inches/hour. The 12Z hires CAM consensus indicates that convection will initially be more terrain-focused, but will also be advancing off the terrain into the open desert locations where forward propagation off to the east and southeast will be expected. Some modest effective shear will be in place, and some loosely organized multicell convection is expected given the instability/shear environment. Some localized storm total rainfall amounts where convective cells become anchored near the terrain may reach as high as 2 to 3 inches, otherwise some spotty 1 to 2 inch amounts will be expected. Isolated areas of flash flooding will be possible going through this afternoon, and this may include impacts to dry washes and burn scar locations. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5x7e-3EkWsj3wL4sfi9ksFTypKgHpL4DHNXOKUHR65PSmQzc_k40We2WIVEskwTFZqmX= cB6dBYWnE9Tp2F-qgJKFT-s$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...MAF...PSR...SLC...TWC...VEF... ATTN...RFC...FWR...RSA...STR...NWC... LAT...LON 37071337 36871226 35851080 35610934 35620716=20 35080572 34310476 33470443 32610444 31980492=20 31750662 31440763 31060900 31171080 31871192=20 32721243 33511316 34151458 35261542 36221527=20 36981437=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) .