Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 09 2025 05:22:48 AWUS01 KWNH 090521 FFGMPD FLZ000-ALZ000-MSZ000-091030- Mesoscale Precipitation Discussion 0408 NWS Weather Prediction Center College Park MD 121 AM EDT Mon Jun 09 2025 Areas affected...Southern MS...Southern AL...Far Western FL Panhandle... Concerning...Heavy rainfall...Flash flooding possible Valid 090520Z - 091030Z SUMMARY...Stationary/slow moving clusters along old outflow boundary/theta-E gradient pose highly focused totals to 4"+ and possible widely scattered rapid inundation flooding overnight. DISCUSSION...04z Surface and RAP analysis shows a solid theta-E gradient across southern GA, southeast AL before dipping near Pensacola, FL before angling northwest into south-central MS with about 4-8 degrees making it subtle. However, total PWat analysis shows the feature much better with long strung out axis of 2"+ total PWats seen well at the 850-500mb layers in CIRA LPW. Recent uptick in southwesterly surface to 850mb flow at 5-15kts results in sufficient isentropic ascent in small clusters (near the angle in far W FL) and utilizing the slightly uncapped 2000 J/kg MLCAPE along the boundary. Upper level flow is generally weak, but with the approach of the stronger upper-level jet upstream in the Plains, is providing some deeper layer effective bulk shear into the 20-30kt range to provide some organization to the convective clusters to keep the downdrafts from collapsing in on the clustered updrafts. Given total PWats of 2" and sufficient 15kt flux, rates of 2-2.5" have been seen in these clusters.=20 Currently the line is still upstream enough that 500-1000 thickness weak and therefore, upstream inflow is about equal to easterly steering flow to keep cells fairly stationary to weakly moving. New updrafts along weak outflow helps to expand the clusters (particularly further west into south-central MS), so isolated totals of 3-5" are becoming increasingly possible resulting in focused possible rapid inundation flooding. As the upstream MCS continues to barrel through eastern Texas, low level inflow will back a bit and WAA should expand convective initiation southern to west-central MS. This increase in inflow is also likely to increase forward cell motions toward the north likely reducing overall totals but increasing coverage of 1-3" totals in advance of the line. Will have to continue to monitor the area into the dawn time frame for subsequent MPDs.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5VbDJ44c3Rmz2iJAcrVXKwhNHGe5Pw8kVwV9suXhlnncytmYwmtK5OYyQnPtS7VPo78q= mZd6sc90VaeBfwjoG71E6uY$ for graphic product... ATTN...WFO...JAN...MOB...TAE... ATTN...RFC...ALR...ORN...NWC... LAT...LON 32608994 31938809 31768645 31388595 30698598=20 30298622 30338699 30488782 30788833 31068944=20 31559031 32149076=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .