Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Dec 10 2023 04:10:05 AWUS01 KWNH 100408 FFGMPD VAZ000-NCZ000-GAZ000-TNZ000-ALZ000-101005- Mesoscale Precipitation Discussion 1193 NWS Weather Prediction Center College Park MD 1106 PM EST Sat Dec 09 2023 Areas affected...Portions of the TN Valley and Southern Appalachians Concerning...Heavy rainfall...Flash flooding possible Valid 100405Z - 101005Z SUMMARY...Isolated to widely scattered instances of flash flooding will be possible overnight across portions of the TN Valley and into the southern Appalachians. DISCUSSION...The latest GOES-16 IR satellite imagery in conjunction with dual-pol radar shows a southwest/northeast axis of heavy showers and thunderstorms with coverage and organization over the last couple of hours that has been on the increase. The latest convective trends are showing some increase in training cell activity, and this will be a concern overall heading through the overnight hours for areas of the TN Valley and the southern Appalachians. All of the convection is focusing along and ahead of a cold front steadily advancing off to the east out ahead of a positively tilted upper-level trough extending from the Lower MS Valley into the OH Valley. MLCAPE values ahead of the cold front are on the order of 500 to 1000 J/kg with a southwest low-level jet of 30 to 40 kts helping to foster a relatively strong axis of moisture transport. The shear profiles are rather strong within the band of convection with as much as 40 to 50 kts of effective bulk shear in place, and this coupled with the available instability is favoring some embedded supercell/mesocyclone activity within the overall linear mode of the convection. Over the next several hours, the southwest/northeast axis of convection should impact areas of northeast AL, northwest GA, eastern TN and southwest NC with heavy rainfall rates that will be capable of reaching 1.5 inches/hour. The 00Z HREF guidance shows the highest rainfall rates generally focusing across northeast AL into southeast TN including parts of the Cumberland Plateau where there will likely be somewhat stronger concerns for training cell-activity. Expect locally as much as 3 to 4 inches to fall going through the overnight hours due to these training convective band concerns and also with localized orographics/upslope flow over the higher terrain that will also favor locally heavier rainfall rates/storm totals. The antecedent conditions across the broader region are quite dry, but with these anticipated storm totals and short-term cell-training concerns, there may be enough rainfall to foster some isolated to widely scattered instances of flash flooding. Orrison ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7iuahKShewsiFCNBETuqAuDdjA3b8uAZJOHDdcVbgqM9cHuo9D-BODBVlyxkPowqUQFM= ppFlNP7pHmNL9aIA19Gv0Wc$ for graphic product... ATTN...WFO...BMX...FFC...GSP...HUN...MRX...OHX... ATTN...RFC...LMRFC...OHRFC...SERFC...NWC... LAT...LON 36648320 36468256 35928270 35398332 34688435=20 33638595 33198699 33308759 33798764 34258707=20 35228567 35948485 36398404=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) .