Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 26 2025 18:47:26 AWUS01 KWNH 261847 FFGMPD NMZ000-AZZ000-270045- Mesoscale Precipitation Discussion 1140 NWS Weather Prediction Center College Park MD 245 PM EDT Fri Sep 26 2025 Areas affected...Central to Southeast AZ...Southwest NM Concerning...Heavy rainfall...Flash flooding likely Valid 261845Z - 270045Z SUMMARY...Expanding clusters of heavy showers and thunderstorms this afternoon will likely drive scattered to numerous areas of flash flooding. Locally significant and life-threatening impacts will be possible. DISCUSSION...The latest GOES-W visible satellite imagery along with radar data shows expanding clusters of heavy showers and thunderstorms across central AZ to the southwest of the Mogollon Rim and to the north of Phoenix, with additional areas of convection also seen developing off to the east and southeast across southeast AZ. All of this convection is developing and expanding in coverage in response to the arrival of a compact closed low over southeast CA which is allowing for notably divergent flow aloft downstream across central and southern AZ while also interacting with a strongly unstable and moist boundary layer. MLCAPE values are on the order of 1500 to 2500 J/kg with 850/700mb moisture flux anomalies of 2 to 3 standard deviations above normal across the region ahead of the approaching height falls. As additional boundary layer heating ensues across the region, there will likely be additional expansion of convection which is expected to become locally quite concentrated across portions of central to southeast AZ. In time this afternoon, convection is also expected to develop farther off to the east into areas of southwest NM, which will have the aid of orographic ascent and differential heating boundaries to support convective development. Rainfall rates will be capable of reaching 1 to 2 inches/hour with the stronger storms, and the environment is highly conducive for pockets of slow-moving cells and backbuilding convection. This may support some rainfall totals reaching 2 to 4 inches by late this afternoon. This is generally supported by the latest HREF/REFS guidance suites. Given the coverage and intensity of the convection that is expected to unfold this afternoon, scattered to numerous areas of flash flooding are expected. This will include concerns for enhanced dry wash/arroyo flash flooding along with potential for areal burn scar impacts. Urban flash flooding will also be a possibility including locations such as Phoenix, Tuscon and Safford. Thus, locally significant and life-threatening impacts will be possible where these heavier rains materialize over the next several hours. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6ZnUcNqjMcMtxd7B7uzBHV7R59cx426Q6EmeUoLpra_febM6hg8lxqJq-jhapBGmxJwk= H6m270gD4kLpom0IjSTkYpQ$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC... ATTN...RFC...FWR...STR...NWC... LAT...LON 35021202 34541068 34470938 34600731 33260674=20 31730756 31150855 31020977 31131108 31611178=20 32301208 33061239 34221308 34871279=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) .