Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 13 2024 00:49:14 AWUS01 KWNH 130049 FFGMPD ALZ000-130645- Mesoscale Precipitation Discussion 1000 NWS Weather Prediction Center College Park MD 848 PM EDT Thu Sep 12 2024 Areas affected...Northwest to Southeast Alabama... Concerning...Heavy rainfall...Flash flooding possible Valid 130050Z - 130645Z SUMMARY...Regenerative thunderstorms along the front will continue to repeat/train northward across central to northwest Alabama.=20 Focused banding to produce 2-4" streaks resulting in scattered possible flash flooding through overnight period. DISCUSSION...Post-tropical cyclone Francine continues a north-northwest track and is nearing the Mississippi Delta southwest of Memphis this hour. Stronger theta-E gradient analysis is helping to determine frontal structures to define a narrow warm sector across southwest Alabama; however, higher Tds are pooling along southeast AL/central FL panhandle, to slightly enhance instability fields along the effective warm/stationary front. This boundary extends from a triple point near KTUP and crosses through TCL to SEM and between GZH and K79J. Stronger return easterly component flow across the FL panhandle into SE AL is also advecting the higher Tds in the low levels resulting in the nose of deeper moisture across SE AL toward MGM. The dry slot through 700mb is out of the SSW and covers much of the warm sector of SW AL but helps to steepen lapse rates across central AL providing higher potential vigor. Proximity to the eastern gradient between the regimes along the front will likely continue to be the area of greatest convergence and rainfall potential given highest flux.=20 Instability is solid at about 1000+ J/kg but given the strength of low level directional shear, some updrafts have been getting sheared before greatest depth is achieved and 10.3um EIR loop shows this with limited cold tops and orphaned cirrus canopies racing northeast. Still, the low level flux convergence given 0.9-1" in the Sfc-850mb layer through the length of the effective warm front allows for efficient rainfall production with 1-1.5"/hr short-term rates while allowing more of a south to north cell motion given depth only is about to 850-750mb. The potential for redevelopment along the strong but stationary front will allow for repeating/training elements with streaks that may align to support localized 2-4" totals. As such, localized flash flooding will continue to be possible, given likely limited movement of the boundary and continued flux as the circulation moves northwest directionally parallel to the frontal orientation. This may further pull the effective cold front back west or allow for return wrap around moisture to over-top the convergence zone across NW AL as well, expanding the potential for an incident or two further up the effective warm frontal zone overnight. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!40hw24sZaVbexQr5LEp1y4Ae-rlWlvyWMZUT6nRKTkBeUBN4DveBR_UkotyvTvJQ2O8j= TiA4cP9T3PjCMP80TEjd2KQ$ for graphic product... ATTN...WFO...BMX...HUN...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 34938736 34548660 33698604 32968568 31548542=20 31108614 31318684 31958737 32708775 33438796=20 33908807 34418813 34838802=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) .