Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 13 2025 15:01:30 AWUS01 KWNH 131501 FFGMPD VAZ000-NCZ000-SCZ000-GAZ000-TNZ000-ALZ000-132100- Mesoscale Precipitation Discussion 0926 NWS Weather Prediction Center College Park MD 1100 AM EDT Wed Aug 13 2025 Areas affected...Portions of the TN Valley...Southern Appalachians Concerning...Heavy rainfall...Flash flooding likely Valid 131500Z - 132100Z SUMMARY...Broken areas of heavy showers and thunderstorms will continue to impact areas of the TN Valley and the southern Appalachians going through the mid-afternoon hours. Additional scattered areas of flash flooding are likely. DISCUSSION...The latest GOES-E IR/WV satellite imagery along with radar shows an expansive axis of broken showers and thunderstorms extending from northern AL through eastern TN, northwest NC and southwest VA. This activity continues to be focused along an elongated axis of mid-level vort energy which is interacting with a combination of very moist/unstable air and favorable orographics near areas of higher terrain. 3-hour MLCAPE differentials off the latest RAP shows a notable increase in instability across areas of eastern AL through northern GA and into the eastern slopes of the southern Appalachians. This instability along with moist southerly flow and influence from differential heating boundaries ahead of the vort energy should favor a general expansion of convection off to the east going through the early and mid-afternoon hours. PWs are locally over 2 standard deviations above normal and the environment is strongly conducive for highly efficient rainfall processes and potentially extreme rainfall rates. Areas of greatest short-term concern may tend to be across northeast AL through far southeast TN and northern GA where visible satellite imagery shows a well-defined differential heating boundary and an agitated CU field expanding in coverage. Additional areas of convection near and just east of the southern Appalachians from northwest SC and western NC into southwest VA will be expected as well with locally very high rainfall rates. Slow-moving cell-motions and the efficient tropical environment will support locally 2 to 3 inch/hour rainfall rates and some spotty storm totals of 3 to 5 inches by later this afternoon. These rains are likely to support additional scattered areas of flash flooding, and especially with locally wet/saturated antecedent conditions. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_fOPX_jkq-ATXh6gnquYJd8ItVsuzAAcrDAqm9NSjWPAJQXv4XeY47xX1cYITDPhyCBU= d8SBy8rAec8NJrPkWaAKdeU$ for graphic product... ATTN...WFO...BMX...FFC...GSP...HUN...MRX...OHX...RNK... ATTN...RFC...ALR...ORN...TIR...NWC... LAT...LON 37218083 36798037 35848104 34808215 34338299=20 33508461 33308591 33408728 33978761 34758682=20 35558556 36318387 36898240=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .