Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 23 2024 23:04:47 AWUS01 KWNH 232304 FFGMPD COZ000-NMZ000-AZZ000-UTZ000-240430- Mesoscale Precipitation Discussion 0924 NWS Weather Prediction Center College Park MD 704 PM EDT Fri Aug 23 2024 Areas affected...Eastern Arizona, far western New Mexico, southern Utah Concerning...Heavy rainfall...Flash flooding possible Valid 232303Z - 240430Z Summary...Showers and thunderstorms will continue to develop and expand across the Four Corners through the evening. Rainfall rates in excess of 1"/hr are likely, which could result in isolated instances of flash flooding. Discussion...The GOES-E visible satellite imagery this evening shows rapid growth of TCu and Cb with overshooting tops developing from southeast Arizona into far southern Utah. These strong updrafts are associated with expanding coverage of convection noted in the regional radar mosaic, while expansive probabilities of lightning-cast exceeding 50% cover much of the Four Corners indicating continued growth potential. The environment is ripe for impressive coverage and intensity of convection through PWs of 1-1.3 inches overlapping MLCAPE of 1000-2000 J/kg. Forcing for ascent is being provided through this destabilization, a weak shortwave lifting northward and exiting the Sonoran Desert, and impressive 700-300mb diffluence arcing towards the Four Corners. This lift into the robust environment is producing radar-estimated rain rates that have briefly reached as high as 1.5-2"/hr. The CAMs indicate that thunderstorm coverage will continue to expand for a few more hours before nocturnal stabilization and convective overturning cause waning this evening. Until that occurs, convection could become widespread, especially in regions of enhanced bulk shear analyzed by the SPC RAP across southern Utah and southeast Arizona. Here, bulk shear of 30-40 kts could help organize thunderstorms into clusters, causing an uptick in rainfall rates which are otherwise progged by HREF neighborhood probabilities to have a 20-25% chance of reaching 1"/hr. These rates will likely result in pockets of 0.5-0.75 inches of rain in a short duration as reflected by HRRR subhourly fields, with progressive storm motions on 0-6km mean winds of 15-25 kts otherwise limiting more significant accumulations. The exception to this could be in southeast AZ or southern UT where storm organization could lengthen rainfall duration, or during storm initiation cross southeast AZ as Corfidi vectors are more collapsed to 5-10 kts suggesting slower motions in that region. Locally, this could result in 1-2" of rainfall in a few locations. 1-hr FFG across most of eastern AZ and southern UT is below 1 inch, and the HREF exceedance probabilities peak around 15-20%. However, NASA SPoRT 0-10cm RSM is elevated above 60% in much of the area, suggesting soils are even slightly more vulnerable. Instances of flash flooding will be most likely across sensitive terrain features like burn scars, dry washes, and canyons, but impacts are possible anywhere the most intense rates can linger through the evening. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9-F66709GrHkaFm2HeIQuxScsay3B70ekEH2_f8HWdcjfZ3xnuLID6hkLEDoMC1D5xgS= 3EcKjbsAskUGyrLOI1_JvGw$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 38331066 38300948 38080901 37750870 36690844=20 35310840 33600860 32240900 31720923 31440986=20 31511064 31891123 32611159 33211162 33801145=20 34631119 35171107 36051092 36801182 37191252=20 37521268 38081187=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) .