Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Mar 25 2023 02:55:36 AWUS01 KWNH 250255 FFGMPD TNZ000-ALZ000-MSZ000-250800- Mesoscale Precipitation Discussion 0127 NWS Weather Prediction Center College Park MD 1055 PM EDT Fri Mar 24 2023 Areas affected...Southern Middle TN...Northern AL...Central to Northeast MS... Concerning...Heavy rainfall...Flash flooding possible Valid 250300Z - 250800Z SUMMARY...Strong supercells and veering low level flow support backbuilding and short-term training resulting in streaks of 2-4" totals continuing flash flooding risk through early morning hours. DISCUSSION...Regional RADAR mosaic depicts a mature QLCS with MCV starting to accelerate across western TN into Middle TN. Solid moisture flux convergence along the leading nose of the squall line will maintain rapid updraft development and support very intense but short-duration rainfall capable of 1-1.5" in less than 30 minutes. This line is starting to outpace the instability and moisture axis which remains further south and west, diminishing the potential for these intense rates as the squall moves toward eastern TN. Further south, however, the veering low level jet/moisture axis relative to the overall cyclone has seen a maintenance of stronger low level flow though convergence is becoming more oblique to the overall line across northeast MS as it enters NW AL. This is now supporting flanking line redevelopment toward the southwest across with a pre-squall line cells also merging into the line as it passes across central MS. Surface flow of 15-20kts with Tds in the 60s, while VWP and RAP analysis show 50-60kts of inflow with GPS and 00z RAOBs still supporting 1.5-1.7" total PWats providing very strong moisture flux convergence. Enhanced by supercellular isallobaric acceleration of into the updrafts, efficient rainfall production will continue through the next few hours with 2"/hr rates likely (with HRRR 15 minute totals of 1.25-1.5" forecast and appear reasonable given local observations). With the veere??d profile and backbuilding along the flanking line, those rates could maintain for an hour or two with short-term training, resulting in storm-scale streaks of 2-4" totals across central to northeast/eastern MS into western AL over the next few hours. Across central MS into AL, soil conditions are a bit drier than further north generally in the 40-50% range per NASA SPoRT LIS products and so higher FFG values are going to be harder to exceed relatively speaking as well. As such, incidents of flash flooding are likely to be more scattered in nature though remain possible though the overnight hours, especially with those training flanking line cells associated with supercells. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8kCj7iKDEK5Zz4T5N-H6GeIeYeXbTCfp0zx-KQ4ugpNTMmu2cMUsStJWbzhkrAhx987q= _SnmFzjNaNku4VPC5Vaviw0$ for graphic product... ATTN...WFO...BMX...HUN...JAN...MEG...MRX...OHX... ATTN...RFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 35798681 35458581 34248562 33338653 32918949=20 33349067 34448960 34888921 35688794=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) .