Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 11 2023 21:18:51 AWUS01 KWNH 112118 FFGMPD FLZ000-GAZ000-ALZ000-120315- Mesoscale Precipitation Discussion 0906 NWS Weather Prediction Center College Park MD 517 PM EDT Fri Aug 11 2023 Areas affected...central/southeastern Alabama, southwestern Georgia, parts of the Florida Panhandle Concerning...Heavy rainfall...Flash flooding possible Valid 112115Z - 120315Z Summary...Deep, vigorous convection has materialized across east-central Alabama and southwestern Georgia. Their orientation has favored prolonged areas of heavy rainfall that could result in isolated flash flooding. over the next 3-4 hours. Discussion...Deep convection materialized along an old outflow boundary from prior convection from near Montgomery through Auburn and Eufaula. Additional storms are located across southern Georgia near Albany. These storms are in a very unstable, moisture-rich environment characterized by 2+ inch PW values and nearly 4000 J/kg MLCAPE - both supporting efficient rainfall processes and strong downdrafts. Of recent concern is the general southeastward movement and orientation of storms to favor convective training. Peak rain rates were estimated at around 3 inches/hr just south of Columbus over the past hour or so. This isn't a surprise as northwesterly mean flow aloft has recently oriented parallel to the axis of heavier downpours. Meanwhile, light low-level westerly flow was helping to maintain advection of the moist pre-convective airmass toward the axis of heavier rainfall and should continue to do so over the next few hours. The degree of convective training over the next 3-4 hours is a bit uncertain, however. Modest low-level shear should allow for gradual upscale growth of convection into forward propagating linear segments which should allow for rain rates to remain mostly in the 1-1.5 inch/hr range. However, should localized training continue (as observed along the AL/GA border south of Columbus), increased rain rates (perhaps 2-3.5 inches/hr) should readily exceed FFG thresholds and pose a flash flood risk on at least an isolated basis. The overall axis of convection is migrating toward weaker wind fields with southern extent, which also may act to slow storm motions and result in additional, isolated flash flooding. Current thinking is that at least an isolated flash flood risk should exists with this activity through 03Z or so - especially if/where training of storms can occur over sensitive and/or urbanized land areas. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4JyfQTNbF2Hvsh4h5Y1ELBe76vMCMjBvAv3Th7mxqD5fim8eJ65bAhV5ZEd4Ho8BBsbS= ylTr6Y_MhXbHZtB7NDPslJ0$ for graphic product... ATTN...WFO...BMX...FFC...JAX...MOB...TAE... ATTN...RFC...SERFC...NWC... LAT...LON 33288713 33268581 32508285 31848261 30328375=20 30288542 31558703 32008727=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) .