Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 12 2023 19:06:36 AWUS01 KWNH 121906 FFGMPD NMZ000-AZZ000-UTZ000-130105- Mesoscale Precipitation Discussion 0913 NWS Weather Prediction Center College Park MD 305 PM EDT Sat Aug 12 2023 Areas affected...Far Western NM...Central/Northern AZ...Southern UT Concerning...Heavy rainfall...Flash flooding possible Valid 121905Z - 130105Z SUMMARY...Scattered monsoonal showers and thunderstorms may produce at least isolated instances of flash flooding through the afternoon hours. DISCUSSION...GOES-W visible satellite imagery shows convective initiation taking place over the higher terrain of far western NM, central to northern AZ and into southern UT, including the Mogollon Rim area. Seasonably moist conditions are largely in place in association with the Southwest monsoon pattern that is in place regionally, and this coupled with the diurnal heating cycle in conjunction with orographics will lead the way for scattered showers and thunderstorms going through the afternoon hours. Strong boundary layer heating is already yielding a moderately unstable airmass with as much as 1500+ J/kg of SBCAPE in place, and this coupled with the moist column will likely yield some intense hourly and sub-hourly rainfall rates. The 12Z HREF guidance favors some of the heaviest rates congregating near the orographically favored Mogollon Rim with hourly rainfall totals that may approach 2 inches, but some sub-hourly amounts of as much as 1 to 1.5 inches in 30 minutes will be possible given the instability and initially strong updraft potential of these cells. The convection overall will tend to have greater coverage over central and northern AZ, but areas of southern UT are likely to see scattered showers and thunderstorms as well with convection locally slow-moving near the always sensitive slot canyons, including areas near Zion National Park. Expect storm totals amounts across the region to locally reach as high as 2 to 3 inches where the cells tend to persist, and these totals coupled with the high hourly and sub-hourly rainfall rate potential in general, should result in a threat for at least isolated instances of flash flooding going through the afternoon hours. Regionally, any area dry washes, slot canyons and burn scar locations will be most vulnerable to seeing enhanced runoff concerns and potential flash flooding going through the afternoon hours. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-OMfcEMEfkRz5-wMmEZxs-ASAfgUEHhDYuFPXVIT5M1r5GFTB6sT470wW_MQJd2a20kC= xS7rG9-YFP_aQ-ESsKQHY58$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC...VEF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 39421125 38901062 36251069 35070947 33850765=20 32590781 33281118 34391281 35861375 37821336=20 39211230=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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .