Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 14 2023 19:19:38 AWUS01 KWNH 141919 FFGMPD ALZ000-MSZ000-LAZ000-ARZ000-TXZ000-OKZ000-150100- Mesoscale Precipitation Discussion 0482 NWS Weather Prediction Center College Park MD 319 PM EDT Wed Jun 14 2023 Areas affected...The Arklatex into western Alabama Concerning...Heavy rainfall...Flash flooding possible Valid 141918Z - 150100Z Summary...Thunderstorms blossoming along a stationary front will expand in coverage and train from west to east through the evening. Rainfall rates in excess of 2"/hr are likely, which in some areas will produce more than 3 inches of rain which could produce flash flooding. Discussion...The regional radar mosaic across the Southeast this aftn shows a rapid expansion of thunderstorms from extreme northeast Texas through the Atlantic Coast of Georgia. These thunderstorms are developing along a stationary front analyzed by WPC, which is serving to enhance low-level convergence to drive ascent. At the same time, a 300mb jet streak of 80-90 kts is moving across OK/TX and impinging into the region, with the resultant isallobaric response driving subtly backed low-level flow out of the Gulf of Mexico. These winds, which are analyzed via VWPs to b e 20-35 kts at 850mb, will lift more orthogonally along the front to enhance isentropic ascent, adding to the already robust deep layer lift over the area. This forcing will work into an extreme thermodynamic environment characterized by PWs measured by GPS of around 1.7 inches, above the 75th percentile for the date, and SPC RAP analyzed SBCAPE of around 5000 J/kg. As the aftn progresses, convection is likely to become widespread and intense as reflected by high-res simulated reflectivity, with storms training along the impressive CAPE gradient collocated with the stationary boundary. Storms will likely move very quickly to the east as progged by 850-300mb mean winds around 40 kts, but aligned Corfidi vectors and robust 0-6km bulk shear of 50-60 kts will support storm organization into multicells and supercells, with training along the front expected. Rain rates within the more intense convection could reach 2-3"/hr, with sub-hourly rain rates progged by the WoFS potentially reaching 5"/hr. This will result in rapid accumulation of rainfall for which the HRRR sub-hourly suggests could reach more than 1"/15 minutes. Where these rates train, more than 3 inches of rainfall is likely as reflected by HREF neighborhood probabilities, with the greatest potential along the immediate vicinity of the front as reflected by the highest EAS probabilities. 1-hr and 3-hr FFG has been compromised from recent rainfall which has exceeded 300% of normal the past 7 days in some areas according to AHPS, including more than 4 inches in the past 24-hrs. While HREF exceedance probabilities are modest, these intense rates could quickly overwhelm soils, especially in urban areas or where FFG is lowest, resulting in instances of flash flooding through the evening. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!97N3POLiItrpKam8SZzTUJhRzEy-pBT9_TPefC6GXld5PhYuMI64kwkHYCWVpsLbiPqB= qV99znnlIVGqjAC6zEYKhHo$ for graphic product... ATTN...WFO...BMX...FWD...JAN...LZK...MEG...MOB...SHV... ATTN...RFC...ABRFC...LMRFC...SERFC...WGRFC...NWC... LAT...LON 34269270 34209066 34028947 33788835 33458755=20 32928721 32378722 31938762 31628842 31559090=20 31989314 32449460 32819544 33299561 33879467=20 34229303=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) .