Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 09 2025 23:55:47 AWUS01 KWNH 092355 FFGMPD VAZ000-NCZ000-SCZ000-GAZ000-TNZ000-100600- Mesoscale Precipitation Discussion 0631 NWS Weather Prediction Center College Park MD 755 PM EDT Wed Jul 09 2025 Areas affected...Southern Appalachians into the Carolinas Piedmont Concerning...Heavy rainfall...Flash flooding possible Valid 092354Z - 100600Z Summary...Showers and thunderstorms will increase in coverage through the next several hours. Rainfall rates within deeper convection will exceed 2"/hr leading to localized rainfall as much as 3-4". Flash flooding is possible. Discussion...The GOES-E IR imagery this evening shows a slow uptick of cooling cloud tops from northern AL through western/central NC. These cooling tops are associated with deepening convection within a belt of higher moisture clearly noted on the GOES-E WV imagery stretching from MS into New England. Embedded in this plume, a potent vorticity max is pinwheeling across central TN, accompanying the primary mid-level trough axis that is concurrently swinging eastward. This is driving mid-level height falls from eastern TN into the Carolinas and western VA, which is combining with S/SW 925-850mb flow and the resulting upslope/convergence into the terrain to produce significant ascent. Additionally, a pre-frontal trough and accompanying squall line are moving across central NC. This lift is acting upon a moist and unstable atmosphere characterized by PWs of 1.8-2.2 inches and MLCAPE that remains above 2000 J/kg, resulting in widespread thunderstorm development noted via the regional radar mosaic. Radar estimated rain rates have been as much as 2"/hr according to KGSP and KMRX, and these are likely to continue for several more hours as reflected by HREF 2"/hr neighborhood probabilities peaking above 30%. This is despite the slow wane of surface instability, as the residual elevated CAPE will be plentiful to support heavy rain. As the shortwave and mid-level trough axis over TN swing eastward, forcing for ascent should maximize over western NC and the surrounding mountains/foothills, leading to an increase in convective coverage. This is suggested by many high-res CAMs, and activity is expected to linger well beyond the typical diurnal maximum. As convection expands, bulk shear may approach 25 kts to help drive at least modest organization into clusters, but with mean 0-6km winds and accompanying Corfidi vectors remaining just 5-10 kts, storm motions will be slow and chaotic. This is concerning for the flash flood potential as the intense rain rates will continue, helping to drive the HREF neighborhood probabilities for 3"/6hr (5"/6hr) above 40% (10%). FFG across the region varies greatly since the mountains have been dry the last 7 days, but the Piedmont is vulnerable due to recent heavy rain. Despite the varying FFG, HREF 3-hr FFG exceedance probabilities peak at 15-30% across much of the region. This suggests a flash flood risk exists across the entirety of the area, with the vulnerable soils east, and sensitive terrain west, increasing the runoff risk through the evening. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7yst06KkSqxdriZn2l8VXmfCjEkwZvmiiIcIq84uP5AtJiEXoeoPAKydVNRpvksH9FSU= IAHKUnrExW804NMw9keUHQ4$ for graphic product... ATTN...WFO...CAE...FFC...GSP...JKL...MRX...RAH...RLX...RNK... ATTN...RFC...ALR...ORN...TIR...NWC... LAT...LON 37118106 36617969 35857935 35087952 34728008=20 34508150 34438283 34558372 34678435 34898482=20 35688476 36588357 36948259=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) .