Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 19 2023 02:21:35 AWUS01 KWNH 190221 FFGMPD ALZ000-MSZ000-190820- Mesoscale Precipitation Discussion 0520 NWS Weather Prediction Center College Park MD 1020 PM EDT Sun Jun 18 2023 Areas affected...Mid-South Concerning...Heavy rainfall...Flash flooding likely Valid 190220Z - 190820Z SUMMARY...Organizing clusters of heavy showers and thunderstorms are anticipated overnight. Locally repeating rounds of this convection coupled with high rainfall rates will likely result in areas of flash flooding. DISCUSSION...The latest satellite and radar imagery shows convection developing and rapidly expanding in coverage across areas of central and northern MS as the left-exit region of an upper-level jet streak rounds the base of an upper trough and associated closed low over the Lower/Middle MS Valley region. This energy is interacting with a warm front attempting to lift back to the northeast into the broader Mid-South and with the pooling of extreme instability along it with MLCAPE values of as much as 3000 to 4000 J/kg. Strong vertical shear in vicinity of the front coupled with this level of instability will yield an environment conducive for supercell thunderstorms heading into the overnight hours. This coupled with PWs in the pre-convective environment of 1.75 to 2 inches based off 00Z RAOB and GPS-derived data is expected to yield extreme rainfall rate potential that may reach 2 to 3 inches/hour. The concern on the rainfall front overnight will not only be the likelihood of seeing these supercell thunderstorms capable of producing extreme rainfall rates, but it will be the upscale growth of convection more broadly across the Mid-South as stronger forcing aloft arrives and coincides with a southwest low-level jet of as much as 30 to 50 kts that will yield rather strong moisture transport/convergence and focusing of instability up along and over the aforementioned warm front. Cell-merger activity and localized repeating rounds of convection will favor areas seeing excessive rainfall amounts with the potential existing for 4 to 6+ inch rainfall totals locally. The 00Z HRRR in particular is extremely wet over areas of central MS and is suggestive of high-impact rainfall. Radar and satellite trends certainly support the greatest rainfall threat existing over areas of central and northern MS over the next few hours, but eventually this threat will extend downstream into areas of western AL. Many areas of central and northern MS, and parts of western AL saw heavy rainfall early this morning which has at least moistened up the soil conditions and increased streamflows to an extent. The additional heavy rainfall tonight, which may be locally significant given the setup, is likely to favor concerns for areas of flash flooding and enhanced runoff potential. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7NtVmzQ3w7IzfNxJmE5sDIy95uYUKktji4_r2d7rU_LtbM8e65GcZgESZzooVQeRGNlV= 1ICH31ZK6hiUd4QXECEJchc$ for graphic product... ATTN...WFO...BMX...HUN...JAN...MEG...MOB... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34708802 34508683 33948646 33018663 32168720=20 31538818 31368943 31639028 32309071 33269022=20 34288918=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) .