Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Oct 01 2023 20:27:40 AWUS01 KWNH 012027 FFGMPD FLZ000-020200- Mesoscale Precipitation Discussion 1121 NWS Weather Prediction Center College Park MD 426 PM EDT Sun Oct 01 2023 Areas affected...eastern to southeastern FL Concerning...Heavy rainfall...Flash flooding possible Valid 012020Z - 020200Z SUMMARY...As isolated flash flood threat will linger across the eastern to southeastern FL Peninsula for another 3-6 hours. The potential for rainfall rates between 2-4 in/hr and additional localized totals between 3-5 inches will remain until 02Z. DISCUSSION...Local radar reflectivity and infrared satellite imagery at 20Z showed that the strongest thunderstorms remained over the southern FL Peninsula, generally south of a cold front that extended west to east across northern Lake Okeechobee. Surface observations and VAD wind plots showed a weak surface low that extended up to 850 mb located near the coast, just northeast of PBI, associated with lingering showers and thunderstorms. Local radar imagery also showed stronger thunderstorms developing along a sea breeze boundary from near BCT southward to near HWO and with approaching outflow boundaries from the north and west. The environment remained supportive of very heavy rain with PWATs between 2.2 and 2.5 inches, MLCAPE of 1000-2000 J/kg and slow steering flow aloft between 5-10 kt (20Z SPC mesoanalysis). Low level onshore flow between 15-25 kt was observed via 925-850 mb VAD wind data near/north of the cold front and weakly convergent flow was observed south of the front near the coastal low. The cold front is forecast to continue a steady but slow movement toward the south this evening, with the strongest low level convergence located near the front but lowering dewpoints and decreasing instability lowering the chances of higher rainfall intensities farther north up the FL coastline. Farther south, surface convergence from the coastal low and a number of mesoscale boundaries (outflow/sea breeze) will support a few more hours of a flash flood threat. The low is forecast by the RAP to dissipate by ~00Z. Slow movement and training of storms could still support localized rainfall rates of 2-4 in/hr along with isolated additional totals of 3-5 inches prior to 02Z. These intense rainfall values will keep an isolated flash flood threat in place over the eastern/southeastern Peninsula, with flash flooding most likely where overlap of higher rates occurs with the urban corridor and wet antecedent conditions due to heavy rain over the past several days for parts of the area. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7g1qP45y4qDZUcRfDQexU1iZxJJPbbjnm1e7P_YHu_WKE0zQuTjVWojBFbsGwH5BbIW9= NnJk0MACHJgC7o8XuF6rTbo$ for graphic product... ATTN...WFO...MFL...MLB... ATTN...RFC...SERFC...NWC... LAT...LON 27888049 27818018 27557996 27107974 26297975=20 25458010 25278040 25378071 25558079 26348067=20 26998064 27488075 27808075=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) .