Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 09 2023 01:54:02 AWUS01 KWNH 090153 FFGMPD TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-090701- Mesoscale Precipitation Discussion 0668 NWS Weather Prediction Center College Park MD 953 PM EDT Sat Jul 08 2023 Areas affected...Ozarks through western TN and KY Concerning...Heavy rainfall...Flash flooding likely Valid 090152Z - 090701Z Summary...Showers and thunderstorms will expand in coverage and train west to east along a stationary front tonight. Rainfall rates of 1-2"/hr are likely, which could produce 2-3" of rain with locally higher amounts. Flash flooding is possible. Discussion...The regional radar mosaic this evening shows showers and thunderstorms rapidly increasing in coverage along the AR/MO border eastward into western KY/TN. This convection is developing in response to increasing deep layer ascent driven by low-level convergence along a stationary front analyzed by WPC and the LFQ of an approaching upper jet streak. Additionally, a weak shortwave noted in the GOES-E WV imagery was rotating eastward into TN. This impressive ascent is impinging into a region of extremely favorable thermodynamics characterized by PWs of 1.8 inches, around the 90th percentile for the date, and MUCAPE of more than 2500 J/kg, both measured via the 00Z/9 LZK U/A sounding. Convection blossoming in this overlap of forcing and thermodynamics has had radar estimated rain rates above 2"/hr resulting in impressive FLASH response of 600 cfs/mi unit streamflow. As the jet streak continues to shift east and impinge more intensely above the front and favorable moisture/instability, convection should continue to increase in coverage along the front. The high-res guidance differs in its evolution tonight, but recent HRRR/FV3/ARW runs suggest thunderstorms will continue to build along the front and then advect slowly eastward. However, low-level inflow will remain generally from the west, originating from higher MUCAPE and PW, suggesting redevelopment will continue to the west. This will result in training as mean 0-6km winds and Corfidi vectors are both westerly at 15-20 kts and aligned to each other and the front. This indicates that convection that develops to the west will repeatedly train to the east, with some organization into multi-cells possible through effective bulk shear of 20-25 kts. With rain rates progged by the HREF to be 1-2"/hr, this will result areas of 2-3" of rain with locally higher amounts. 7-day rainfall across the area has been generally above normal, with pockets of more than 300% of normal in MO/AR and southern TN, including 2-4" in the past 24-hrs as measured by MRMS. This has lowered FFG to as low as 1.5"/1hr and 2.5"/3hrs, which could be exceeded by the training of these intense rain rates, leading to instances of runoff and possible flash flooding. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-h6IhhcaZ4H0-_NeSKf_sQTNDyf3qjvp9iOo69FvmX3CCsu4rhndb1gSzCL1P1hZdzEV= XgPq4vnsSiO4VpzGawUSQUs$ for graphic product... ATTN...WFO...LMK...LSX...LZK...MEG...OHX...PAH...SGF...TSA... ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC... LAT...LON 38378644 38198557 37668547 36978584 36268649=20 35748731 35368855 35348977 35519115 35649222=20 35809291 36039338 36429304 36819216 37309054=20 37998813 38218735=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) .