Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Dec 14 2022 07:44:13 AWUS01 KWNH 140744 FFGMPD ALZ000-MSZ000-LAZ000-TXZ000-141400- Mesoscale Precipitation Discussion 1161 NWS Weather Prediction Center College Park MD 243 AM EST Wed Dec 14 2022 Areas affected...Southwest to Central LA...Much of MS...Ext Southeast TX...Ext Western AL... Concerning...Heavy rainfall...Flash flooding likely Valid 140800Z - 141400Z SUMMARY...Slowing forward propagation likely to maintain favorable training environment into early morning hours. Incidents of flash flooding becoming likely with 3-5" totals possible through 15z. DISCUSSION...Regional RADAR mosaic depicts a mature squall line/QLCS slowly progressing across W MS angling back into central LA with an inflection/MCV lifting northeastward across central TN. Larger scale cyclone shows approaching shortwave with baroclinic cirrus shield along/ahead of it across W TX. This has allowed for a slight slacking of the winds, but also is increasingly supporting a favorable unidirectional steering flow that is orienting parallel to the QLCS. This will continue to strengthening probability for training thunderstorms through the line.=20 07z surface analysis shows anomalous Theta-E ridge across S LA into SW MS, up to the warm front that appears to be from the AR/LA/MS corner north of Jackson toward Mobile. Sfc Tds of low 70s reduce slightly to mid 60s supporting fairly unstable environment with SBCAPEs up to 1500 J/kg as far north as Yazoo/Humperies county. This available buoyancy will likely maintain convective strong convective development. Given sfc to boundary layer flow remains fairly oblique to the squall line, while flow above veers, suggests sufficient moisture convergence through the early morning hours. Additionally, given even veering 850-800 lfow and sharpening 500-1000 thickness packing, suggest forward propagation will be reducing further allowing for upstream redevelopment to train.=20 Hi-Res CAMs continue to be fairly solid in timing and evolution to have increased confidence in this unfolding flash flooding scenario. While there is still some uncertainty in magnitude with 00z ARW suggesting as high as 5-6", most suggest 3-4+" including the HRRR which supports strongest updrafts capable of 15min totals of 1" through 12z. All considered, given rates, anomalous moisture and training...flash flooding is considered likely through 14z across Central MS into Central LA. Further southwest along the line, convergence remains less tight due to further weaker winds. However, toward the end of the MPD valid time after 12z, approaching height-falls should back the low level flow and increase WAA strengthening potential for greater converge. Still flash flooding potential remains scattered and probable in localized areas through morning here as well. The greatest uncertainty is along the northeast edge of the MPD area of concern into NE MS/W AL. Here, instability is reduced and also elevated in nature, reducing the potential for stronger deeper convective cores. However, favorable divergence aloft and strong/broad upglide into the TROWAL will support modest rain rates and totals across areas of lower FFG. While this may not induce flash flooding, prolonged heavy rainfall should result in longer duration flooding which could have embedded short-term bursts/rates up to 1"/hr.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5aGsgWgNCoh-w3N8LHtZCiu30UuBCzVdqO95LMrc-ZYeiYDsj8LtuWDf9ZkqRmQeBshD= qRymc5XYNdChUyChuQzxUtw$ for graphic product... ATTN...WFO...BMX...JAN...LCH...LIX...MEG...SHV... ATTN...RFC...LMRFC...SERFC...WGRFC...NWC... LAT...LON 34338912 34198796 33388807 32478873 31908936=20 31199038 30469152 29879235 29949319 29939414=20 30349444 30939376 31859214 32749115 33609013=20 =20=20=20=20=20=20=20=20=20=20=20=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) .