Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 25 2024 17:57:19 AWUS01 KWNH 251757 FFGMPD NMZ000-AZZ000-UTZ000-252355- Mesoscale Precipitation Discussion 0726 NWS Weather Prediction Center College Park MD 155 PM EDT Thu Jul 25 2024 Areas affected...Southern UT...Much of AZ...Far Western NM Concerning...Heavy rainfall...Flash flooding possible Valid 251755Z - 252355Z SUMMARY...Scattered monsoonal convection will be developing soon across the Southwest. Areas of southern UT, far western NM and a relatively large area of AZ should see scattered areas of showers and thunderstorms that will again be capable of producing heavy rainfall and mainly isolated areas of flash flooding. DISCUSSION...GOES-W Day Cloud Convection RGB satellite imagery along with the ML-driven LightningCast product suggests CI will be occurring very soon over areas of southern UT and down through at least central AZ as strong boundary layer heating/destabilization continues and couples with orographic ascent/forcing for scattered showers and thunderstorms. SBCAPE values are locally already on the order of 1000 to 2000 J/kg, and these values will increase over the next few hours which coupled with a seasonably moist monsoonal moisture regime should favor expanding areas of at least scattered convection with heavy rainfall rates. The convection should generally be pulse in nature given the lack of shear underneath the deep layer subtropical ridge that is overhead, but the thermodynamic environment should favor some rainfall rates reaching 1 to 2 inches/hour with the stronger cells. In some cases, as much as 1 inch of rain may fall in as little as 20 to 30 minutes. Initially the activity should have a terrain-focused concentration, but eventually the convection will move off the terrain and into the open desert areas where boundary layer instability will be greater. This will especially be the case across areas of central and southern AZ away from the Mogollon Rim. The 12Z HREF guidance again appears largely underdone with the localized rainfall potential given the concentrations of mid-level moisture that remain in place. The expectation is for some spotty 2 to 3 inch rainfall totals with the stronger storms and especially where any cells tend to remain focused or anchored near the terrain. Some isolated areas of flash flooding will be possible where these stronger pulse cells evolve today. Once again the areal slot canyons, burn scar locations over the high terrain, and normally dry washes/arroyos away from the terrain will be most susceptible to seeing flash flooding impacts. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6whL0BtxIFQ0SKTzJ8TXVbV59RHP-DVVnjTHxNaJMaT_YxzProdTD2PZciQxrYbegcwR= GMUEUNe2OvDXAHnOImmABsY$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC...VEF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 38941179 38341072 37391035 36190911 35070885=20 33470819 32850840 32050942 31361017 31241126=20 31421201 32101281 33651299 35031375 36511329=20 38201338=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) .