Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Nov 02 2024 16:37:34 AWUS01 KWNH 021637 FFGMPD TXZ000-OKZ000-KSZ000-NMZ000-022200- Mesoscale Precipitation Discussion 1113 NWS Weather Prediction Center College Park MD 1236 PM EDT Sat Nov 02 2024 Areas affected...Far eastern New Mexico, Texas Panhandle, western Oklahoma Concerning...Heavy rainfall...Flash flooding possible Valid 021635Z - 022200Z Summary...Convective cells are expected to regenerate along an outflow boundary and track E/NE through the afternoon. Rainfall rates in excess of 1"/hr are likely, resulting in axes of 2-3" of rain with locally higher amounts. This could result in instances of flash flooding. Discussion...A longwave trough centered over the Great Basin is amplifying this morning as evidenced by RAP height falls across that region. This is resulting in sharpening downstream SW flow tapping moisture from the Pacific, and PWs of 1.1 to 1.3 inches have surged into the TX Panhandle, near daily records for early November. Into this moisture, deep layer lift is increasing as height falls and divergence downstream of the primary trough axis increase, and overlap with an impressively coupled jet structure to produce diffluence aloft. This ascent is being enhanced by mesoscale lift as low-level southerly flow from south Texas surges northward on 850mb winds of 20-30 kts, lifting isentropically atop an outflow boundary evident on the regional radar mosaic. Although this outflow boundary is progged via hig-res guidance to continue to shift progressively E/SE, this isentropic ascent should result in regeneration and training of cells through the aftn. Rainfall rates in current convection are generally modest, but MRMS 1-hr rainfall accumulations suggest isolated instances of 1-1.5" of rain in the past hour. These rain rates are somewhat minimized by a lack of pronounced instability, as the SPC RAP indicates a sharp MLCAPE gradient from 250-1000 J/kg across the southern TX Panhandle. As the 850mb LLJ continues from the south however, there is good agreement that these more robust thermodynamics will surge northward, reaching 1000-2000 J/kg this aftn. This should result in increased coverage of rainfall rates exceeding 1"/hr as progged by both HREF and REFS hourly rain rate probabilities. At the same time, mean 0-6km flow will remain around 30 kts from the S/SW, suggesting cells that regenerate along the SW portion of this outflow as it stalls will shift N/NE and train. This indicates potentially two axes of heavy rainfall: one along this SW flank where cells repeatedly develop, and a second maxima into western OK where mean flow is more parallel to the boundary to enhance training. In both these areas, HREF neighborhood probabilities for 3"/6hrs reach 40-50%. Somewhat limiting to the flash flood potential today is exceptionally dry antecedent conditions reflected by AHPS 30-day rainfall that is generally less than 25% of normal, leading to NASA SPoRT 0-40cm soil moisture that is around the 10th percentile. This suggests that flash flooding should primarily be isolated the next several hours, but where any of these 1-2"/hr rates train/regenerate, instances of flash flooding will be possible. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_sivuCLqYWpUQiub-d02x7hSO9eQHxahb4Oq6eMz4jPq8QnsL-Ao_dEApWdSLfLdFcmJ= C2zuhuEeXPDLEwAeJ1F0xP8$ for graphic product... ATTN...WFO...ABQ...AMA...DDC...ICT...LUB...MAF...OUN... ATTN...RFC...ABRFC...WGRFC...NWC... LAT...LON 37109866 36999825 36129816 35579814 34769848=20 34139894 33380018 33070197 33050336 33220390=20 33780416 34500396 35100278 35530133 35930028=20 36599923=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) .