Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 15 2023 18:11:30 AWUS01 KWNH 151811 FFGMPD FLZ000-GAZ000-ALZ000-MSZ000-160000- Mesoscale Precipitation Discussion 0489 NWS Weather Prediction Center College Park MD 210 PM EDT Thu Jun 15 2023 Areas affected...Deep South Concerning...Heavy rainfall...Flash flooding likely Valid 151806Z - 160000Z Discussion...A mature MCS continues to evolve this afternoon across portions of southern GA and northern FL. Upwind development and training of new cells on the western flank of the cold pool/composite outflow will maintain a flash flood threat through this afternoon. Summary...Current radar and IR mosaic imagery across southern GA and northern FL highlight a mature MCS which evolved from earlier supercell and multi-cell cluster mergers. Across northeast FL, velocity data from KJAX sampled a southeast propagating cold pool along the leading edge of the line. Meanwhile, upwind development of individual cells was noted along the cold pool/composite outflow across the FL Panhandle into far western AL, with 30-40 kt easterly storm motions along the 850-300 mb mean wind vector. Within the most organized convection, MRMS hourly rain rates varied from 1-2.5"/hr, leading to a swath of elevated FLASH CREST responses and several Flash Flood Warnings over the last few hours as the activity trains from west-east.=20 25-30 kts of southwesterly 925-850 mb flow will continue to support new convective development as strong moisture and instability transport atop the composite outflow. Owing to the strong moist advection regime, the latest RTMA suggests a considerable uptick in PWATS and MLCAPE over the last three hours across northeast FL and southern GA (.5" and 1000-1500 J/kg, respectively). The favorable inflow and thermodynamics will interact with an approaching shortwave over the TN Valley, increasing diffluence aloft, and strong effective bulk shear (50-60 kts) to maintain convective intensity and longevity through this afternoon. Low level inflow is also forecast to remain favorably oriented to the boundary and for additional east-west training of new cells. Over the next several hours the 12z HREF suggests this activity will begin to forward propagate to the southeast along the Corfidi vector as cells continue merging. However, given the previous very heavy rainfall from ongoing activity additional flash flooding is considered likely as rainfall totals of 2-4" suggested by the 12z HREF are expected through 0z. Asherman ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5JBnRsnCIS57h-xN369adtR6DNvd0-HjnTM-KNEZUBMQZ_LfB0HTrsnScg8FjieWpbFY= 4C3GOq-rE_-0DnYM1VecDPg$ for graphic product... ATTN...WFO...BMX...FFC...JAN...JAX...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 32878878 32628606 31858312 31048145 30358128=20 29968164 29848218 29998342 30398471 31028688=20 31698868=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) .