Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 22 2024 06:36:38 AWUS01 KWNH 220636 FFGMPD NMZ000-AZZ000-221100- Mesoscale Precipitation Discussion 0690 NWS Weather Prediction Center College Park MD 235 AM EDT Mon Jul 22 2024 Areas affected...Southwest New Mexico Concerning...Heavy rainfall...Flash flooding possible Valid 220635Z - 221100Z Summary...Thunderstorms across Southwest New Mexico will continue a few more hours before exiting south into Mexico. Brief rainfall rates in excess of 1"/hr could cause instances of flash flooding. Discussion...Showers and thunderstorms continue across portions of Southwest New Mexico tonight as noted in the regional radar mosaic. There are generally two ongoing clusters of convection: 1) directly downstream of a shortwave and accompanying outflow boundary (OFB) from earlier convection, and 2) within moist and upslope flow out of the Rio Grande Valley and into the Sonoran Desert. The environment across all of the region is favorable for additional development. Forcing remains sufficient in a region of enhanced mid-level diffluence downstream of the most significant PVA, which could expand convection as this drops southward, and this is acting upon robust thermodynamics noted by MLCAPE of 500-1000 J/kg according to the SPC RAP analysis overlapping PWs of 1.1 to 1.3 inches as measured by GPS. The outflow boundary is tracking southward rapidly, and time-of-arrival estimates suggest it will reach the border with Mexico in 2-3 hours. The associated convection should help overturn the environment, and recent 3-hr MUCAPE changes have been falling behind this boundary. However, the accompanying ascent will move into an even more favorable environment as E/SE flow enhances the theta-e ridge near the Mexico/US border, which will support not only additional thunderstorm development downstream of the OFB, but could also act to intensify thunderstorms along the OFB as it moves south. Bulk shear is minimal, but storm mergers and boundary collisions could additionally enhance rainfall rates, which are progged by the HREF to have a 30% chance of exceed 1"/hr. Although convection along the OFB will be progressive, storms that fire ahead of it will likely be slow moving as Corfidi vectors aligned back into the 850mb inflow become increasingly anti-parallel to the mean winds which are slow at just 5-10 kts. Where pre-OFB thunderstorms move slowly with the intense rain rates, followed by any convection along the advancing boundary, rainfall could reach 1-2" in a short period of time, with HREF 3" probabilities indicating a low chance (10-20%) for isolated amounts to 3". These rainfall rates themselves could result in rapid runoff and instances of flash flooding, but flash flooding will be most likely where any slow moving storms ahead of the OFB cause a lengthening of these rates to increase rainfall amounts, or should an intense cell move across the most sensitive terrain features or burn scars. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6UW0MQ42l6yYiQ7HFq5MTpkeQWHqf1Jzlr8ht_HOryiREmty3DMkBiCmpb7JnvST8n-E= 39GrspsbJY2Cm9D-TGB0Nxk$ for graphic product... ATTN...WFO...ABQ...EPZ...FGZ...TWC... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 34470799 34350703 34010607 33340599 32780623=20 32340656 31920679 31580719 31260796 31230846=20 31260891 31660923 32960919 34420894=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) .