Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 29 2024 17:35:24 AWUS01 KWNH 291735 FFGMPD TXZ000-NMZ000-AZZ000-292330- Mesoscale Precipitation Discussion 0755 NWS Weather Prediction Center College Park MD 134 PM EDT Mon Jul 29 2024 Areas affected...Lower Colorado River Basin into southern New Mexico Concerning...Heavy rainfall...Flash flooding possible Valid 291734Z - 292330Z Summary...Showers and thunderstorms will gradually blossom across portions of the Southwest this afternoon. These storms will be slow moving, and may have rainfall rates exceeding 1"/hr at times. Locally this could result in 1-2" of rainfall and scattered instances of flash flooding. Discussion...The GOES-E Day Cloud Phase RGB imagery late this morning shows the initial phases of cloud glaciation occurring in far southeast Arizona and southern New Mexico. This is reflective of strengthening updrafts and deepening Cu/TCu, further evidenced by the GOES-E lightning cast product already exceeding 50% in the Sacramento Mountains. This convective cloud coverage is expanding within favorable thermodynamics noted by PWs measured by GPS of 1-1.5", above +1 standard deviations from the climatological mean, and SBCAPE as high as 1500-2000 J/kg. Although forcing is modest across the region, there is sufficient overlap of ascent and thermodynamics that convective coverage should expand through peak heating. A weak shortwave over the Sonoran Desert and at least subtle RRQ diffluence aloft should aid lift that will otherwise be confined to terrain or boundary interactions. The greatest coverage of storms is likely over southeast AZ which is supported by the high-res CAMs, and short duration rainfall rates in the deeper cells could exceed 1"/hr as shown by the HREF neighborhood probabilities, leading to 1-hr rainfall of 0.75-1.5" as noted by the UA WRF. Bulk shear will remain quite weak at less than 20 kts, indicating generally pulse thunderstorms, and mean cloud layer winds of just around 5 kts suggest storms will be very slow moving. Cells that form along higher terrain features or through any outflow collisions could exhibit nearly stationary motion at times, leading to slightly enhanced rainfall in these areas. With FFG across the region as low as 0.5-0.75"/1hr, and 0-10cm RSM from NASA SPoRT generally 50-70%, it is possible that any cell could quickly cause runoff leading to flash flooding. The most likely areas will be over any sensitive terrain and burn scars, but scattered impacts due to flash flooding are possible anywhere across the area through the afternoon, with additional potential continuing well into the evening. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9aEWASQnRCcB8CBWDTHZK1K_cAb1kjZQAQgblQzPJzLChpfDzlCPueISuwr6ty9hfjsi= VTalig8c2xp1BJLvU-NVEcI$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 34340798 34050761 33730717 33640663 33720620=20 33930598 34140585 34280545 33780514 32830520=20 32240561 31720605 31470662 31160776 31050977=20 31151119 31241164 31891297 32581283 32901213=20 32921155 33241082 33750996 34270901=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) .