Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 23 2023 18:28:21 AWUS01 KWNH 231828 FFGMPD TXZ000-NMZ000-240025- Mesoscale Precipitation Discussion 0965 NWS Weather Prediction Center College Park MD 227 PM EDT Wed Aug 23 2023 Areas affected...western TX into southern/south-central NM Concerning...Heavy rainfall...Flash flooding possible Valid 231825Z - 240025Z Summary...Flash flood potential is expected to increase across portions of southern NM into western TX through early evening. Rainfall rates of 1-2 in/hr are expected, supporting isolated to widely scattered areas of flash flooding. Discussion...Available surface observations and visible satellite imagery at 18Z placed the surface low from T.D. Harold in southern Jeff Davis County. The central pressure has continued to steadily rise over the past 6-12 hours, estimated to be near 1012 mb with a motion toward the NW near 20 kt. However, the surface low is expected to become poorly defined late this evening, becoming less of a direct factor in the flash flood threat. Visible imagery showed cloud streets over the southern Permian Basin and Trans Pecos region of TX, swirling around the low level 850-700 mb circulation from Harold, highlighting the transport of anomalous moisture toward the north and west. 12Z soundings from MAF, EPZ and DRT showed precipitable water values above the 90th percentile or about a +2 standardized anomaly for western TX, and solar insolation through filtered cloud cover is allowing for the generation of MLCAPE from near INK to Big Bend N.P. of about 500-1000 J/kg via the 18Z SPC mesoanalysis. Decreasing cloud cover across portions of southeastern NM into western TX and the combination of increasing surface temperatures with daytime heating should support the expansion of MLCAPE with short term forecasts from the RAP showing 500-1500 J/kg by 22Z from southeastern NM across the western TX/NM border, southward to the Rio Grande. Showers were already developing over Brewster County via satellite imagery where skies had cleared earlier in the day, overlapping with earlier heavy rainfall, but the strongest 850-700 mb flow (20-30 kt) will spread northwestward into the Sacramento and northern Guadalupe Mountains through 21Z, allowing for an upslope component to broader scale lift across the region. Expected veering of the 850-700 mb wind through 00Z will cause better alignment of the low level wind with the deeper-layer steering flow, supporting the potential for short term training and repeating cells. The environment will be capable of producing 1-2 in/hr rainfall rates, but with potential for ~1 inch in 30 minutes. Larger scale forcing, tied to low level convergence with ongoing showers approaching El Paso, is likely to continue to advance toward the northwest over the next few hours with the translation of the 850-700 mb low. However, thick cloud cover across the region from near El Paso into the I-25 corridor and westward casts some doubt on future instability availability given poor mid-level lapse rates to support rainfall rates above 1 in/hr. Across this portion of the forecast area, flash flooding may be limited to burn scar regions and other locations with poor drainage. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4goPvHoZrRXXNOB-NkMlUQY18KD1fIqMbCkt7VNyY5mq9bUxxWjSHQmBZOUn-Mqxl3Sc= K43upb_15Wv2I2k1tLrksvI$ for graphic product... ATTN...WFO...ABQ...EPZ...MAF... ATTN...RFC...CBRFC...WGRFC...NWC... LAT...LON 34420654 34320591 33950501 33310435 32560382=20 32180353 31540316 30380258 29810245 29300277=20 29480355 30390413 30730487 30780539 30980591=20 31540658 31830703 32310770 32810799 33250796=20 33690784 34050758 34370711=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) .