Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Oct 12 2023 09:29:17 AWUS01 KWNH 120929 FFGMPD FLZ000-GAZ000-121525- Mesoscale Precipitation Discussion 1144 NWS Weather Prediction Center College Park MD 528 AM EDT Thu Oct 12 2023 Areas affected...northern FL into southeastern GA Concerning...Heavy rainfall...Flash flooding possible Valid 120925Z - 121525Z Summary...A localized flash flood threat will continue early this morning for portions of northern FL into southeastern GA from training rainfall rates of 1 to 3+ in/hr. Additional rainfall totals through 15Z of 3 to 6 inches may occur. Discussion...09Z surface observations showed a warm front just north of AAF and CTY, with a 5-7 degree rise in surface dewpoint observed between 07-08Z. Regional radar imagery showed mainly stratiform rainfall north of the warm front with stronger and increasingly discrete cells near and south of the warm front. MLCAPE was estimated to be 500 to 1000+ J/kg along and south of the warm front with a sharp dropoff in instability north of the front per 09Z SPC mesoanalysis data. A surface low was analyzed ~50 miles south of PNS with a cold front extending SW from the surface low into the central Gulf of Mexico along with a pre-frontal convergence axis extending SW from near Panama City. Strong moisture flux from the south was occurring ahead of the cold front with nearly 50 kt of 850 mb flow observed on the TLH VAD wind and PWATs likely over 2.5 inches along the Forgotten Coast and into portions of the northern Peninsula via recent SPC mesoanalysis data. With the exception of an area of cell training just southeast of Panama City at 09Z, hourly rainfall rates have decreased in=20 overall coverage and magnitude since 06Z over northern FL. It appears this lull will be temporary however, with short term forecasts from the RAP indicating the surface warm front will continue to lift north through 12Z, becoming oriented favorably to the mean steering flow from the SW. As the surface low and warm front lifts north, the rapid rise in low level moisture following the warm frontal passage will coincide with an increase in instability supporting the potential for very high rainfall rates with peak rates of 1 to 3+ in/hr. Continued strong moisture transport and convergence along the warm front is expected to support areas of cell training with a focus for the heaviest rain possibly focusing from northeastern FL into southeastern GA where multiple rounds of more discrete cells to the south join with convection near and just north of the warm front. The potential for additional rainfall totals of 3-6 inches will remain over the region although these higher end values are likely to remain localized. A flash flood threat will continue through 15Z, especially across urban locations or low lying areas of poor drainage. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!_FsAfrgM_t4jne2oNeCuUoQ-wA8iqfK4ruZgcYsTeIj-RKfHl4McQldFqtXYAVG1LeS0= uGcxZixsrsOvowLr3YhJcoQ$ for graphic product... ATTN...WFO...CHS...JAX...MLB...TAE...TBW... ATTN...RFC...SERFC...NWC... LAT...LON 31628089 31108101 30778109 30208111 29338079=20 29298078 28678289 29118348 29488531 30028570=20 30228560 30538501 30778448 30908379 31158295=20 31328240 31448177=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) .