Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 16 2023 02:50:55 AWUS01 KWNH 160250 FFGMPD LAZ000-ARZ000-TXZ000-OKZ000-160848- Mesoscale Precipitation Discussion 0496 NWS Weather Prediction Center College Park MD 1049 PM EDT Thu Jun 15 2023 Areas affected...Portions of the Red River Valley of the South Concerning...Heavy rainfall...Flash flooding possible Valid 160248Z - 160848Z SUMMARY...Well-organized showers and thunderstorms with very heavy rainfall rates coupled with concerns for cell-mergers and repeating cell-activity over the next several hours will foster concerns for additional isolated instances of flash flooding. DISCUSSION...The latest GOES-16 IR satellite imagery shows clusters of strong to severe thunderstorms with very cold convective tops organizing and advancing off to the east-southeast across the Red River Valley of the South. This is all in association with a rather strong shortwave trough ejecting out across the southern Plains which is interacting with a well-defined quasi-stationary front and the pooling of an extremely unstable and very moist airmass along it. In fact, MLCAPE values along and south of the front are on the order of 5000 TO 5500 J/kg, and with PWs on the order of 1.75 inches. Surface dewpoints are as high as the mid to upper-70s across much of north-central to northeast TX. All of this coupled with very strong effective bulk shear values (60 to 80 kts) has already been fostering long-lived supercell activity, and over the next few hours, there will likely be some cell-merger activity and upscale growth of convection into a larger scale and forward-propagating MCS. As these cell-mergers occur, and aside from well-defined severe weather hazards (see SPC's latest MDs for more details), there will be locally extreme rainfall rate potential with these evolving and consolidating supercells. An increasing low-level jet this evening will maintain a well-defined and extremely favorable moisture/instability transport regime for convective sustenance going well into the overnight hours, and especially with the level of shear that is in place. Expect some rainfall rates to easily exceed 2 inches/hour with the stronger supercells. Some localized 3 to 5 inch rainfall totals cannot be ruled out where some of these cell-mergers occur and locally repeat over the same area over the next several hours. Based on this, there will be a concern for at least isolated instances of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8vuVzh_G3bp70BkPgYWpoB_BurpsnJu7zTx4_1XbnHRWELqV0o2RxqYJXJCaPylwHxqC= y6xv1PbydsbwYoS2rhRbHDU$ for graphic product... ATTN...WFO...FWD...OUN...SHV...TSA... ATTN...RFC...ABRFC...LMRFC...WGRFC...NWC... LAT...LON 34789560 34169454 32499365 31549421 31669565=20 32609693 33769767 34779726=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) .