Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 20 2023 16:32:34 AWUS01 KWNH 201632 FFGMPD NCZ000-GAZ000-TNZ000-KYZ000-202200- Mesoscale Precipitation Discussion 0771 NWS Weather Prediction Center College Park MD 1231 PM EDT Thu Jul 20 2023 Areas affected...Southern KY...Middle and Eastern TN...Southwestern NC Concerning...Heavy rainfall...Flash flooding likely Valid 201625Z - 202200Z Summary...Training thunderstorms continue across portions of middle and eastern TN, with convection filling in to the west ahead of the approaching complex over southern KY. Continued rainfall will maintain a threat of flash flooding going into the afternoon. Discussion...Efficient thunderstorms continue to train across portions of middle and eastern TN along the periphery of an outflow-reinforced stationary front. This earlier training activity with 2-2.5"/hr rates produced 4-6 inches of rainfall according to MRMS Q3 over the last 6 hours northeast of Cookeville. Meanwhile, thunderstorms are beginning to fill in to the west, ahead of the complex over southern KY. As mentioned in MPD 770, the activity remains tied to an axis of favorable low-level convergence along the front overlapped with enhanced right entrance forcing and diffluence aloft with a speed max over the OH Valley. Proximity soundings of the vicinity of this activity show highly saturated vertical profiles (80-90%) with 2.17" PWATS noted over central TN by GPS data, warm cloud layers of 12-13,000 ft, and increasing MUCAPE of 3000-4000 J/KG. 25-35 kts of bulk shear (primarily driven by speed shear within unidirectional flow) will also support some organization and dynamic lift with this activity, but could also result in more progressive individual storm motions. Going forward, training of the activity filling in to the west is expected within a region of thickness diffluence and 3000-4000 MUCAPE upstream noted over western TN. A noted minimum in MUCAPE may limit rates somewhat across the eastern portion of the MPD area, but given the overall favorable environment, rates upwards of 1.5-2.5"/hr appear reasonable. This would easily breach the 1-3 HR FFGs in the area, which as of this morning hovered around 1-2"/hr and 1-2.5"/3hr, respectively. Accordingly, the 12z HREF shows elevated probabilities of 1-3 HR FFG exceedance through 18z, with a signal noted continuing into this afternoon. Given the ongoing flash flooding, favorable environment, and signal from hi-res guidance, flash flooding is considered likely going into this afternoon. Asherman ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4qiDmxeh8B8BpRhSicvZ8V-VTRx6SMXgVLvmMVJwa3hiximuL4-ojViiEzj8siswCC2U= 1m9GiGtsVAEJVXScGBtCPCg$ for graphic product... ATTN...WFO...FFC...GSP...HUN...JKL...LMK...MRX...OHX...PAH... ATTN...RFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 37638690 37078524 36108343 34908359 35018550=20 35438683 36418740=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) .