Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 15 2025 19:06:39 AWUS01 KWNH 151906 FFGMPD TXZ000-NMZ000-AZZ000-UTZ000-160100- Mesoscale Precipitation Discussion 0939 NWS Weather Prediction Center College Park MD 304 PM EDT Fri Aug 15 2025 Areas affected...Southern UT...Much of AZ...Western and Central NM Concerning...Heavy rainfall...Flash flooding possible Valid 151904Z - 160100Z SUMMARY...Increasing coverage of locally heavy showers and thunderstorms can be expected going through the afternoon hours. Isolated to scattered areas of flash flooding will be possible, and especially given slow cell-motions and potential for impacts around the more sensitive dry wash, burn scar and slot canyon locations. DISCUSSION...The midday GOES-W visible satellite imagery shows three well-defined mid-level vort centers collectively embedded within deeper layer south-southwesterly mid-level flow over AZ and NM. The energy over the northern part AZ will be gradually approaching areas of southern UT over the next few hours which coupled with favorable orographics and an uptick in boundary layer instability should help drive the development and expansion of some shower and thunderstorm activity here. However, the more notable threats for stronger convection will likely be with the energy over southeast AZ and southwest NM where there is already locally strong diurnal heating and presence of an instability gradient/differential heating boundary that will help facilitate convective initiation. SBCAPE values over southeast AZ are locally over 1500 J/kg and close to 1000 J/kg along the northern AZ/southern UT border. The PWs are rather concentrated in the 500/700 mb layer based off the CIRA-ALPW data, and especially over southeast AZ and into west-central to southwest NM. On a regional basis, there should be the development and expansion of shower and thunderstorm activity that will be rather slow-moving and locally anchored near areas of higher terrain. More concentrated cells will be possible in close proximity to the vort centers as they lift off to the north and northeast. This convective evolution is supported by the latest hires WoFS guidance. Rainfall rates of up to 1 inch in as little as 20 to 30 minutes will be possible. However, some localized storm total amounts of 2 to 3+ inches may occur given the slow cell-motions and terrain-focused activity. Some of the hires CAM guidance led by the NAM Conest, FV3 LAM and RRFS supports this. This will drive isolated to scattered areas of flash flooding potential which will mainly be focused on the dry wash, burn scar and slot canyon locations where there are greater sensitivities and concerns for enhanced runoff. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4Q1S0K-RnM736tvhuutPocJgepsOULovU9Yitc0OtHMiCN5iD6Di2e1FRQ_RNmE0xLoq= gSgGBqg6-erfvWHJE4uqyBw$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC...VEF... ATTN...RFC...FWR...STR...NWC... LAT...LON 38381223 38251075 37660985 37060924 36410774=20 36040614 35350532 34380504 33280509 32460503=20 31800532 31430580 31300655 31210772 31040956=20 31221120 32011207 33351214 34561257 35731323=20 37601317=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) .