Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 22 2023 03:18:46 AWUS01 KWNH 220318 FFGMPD FLZ000-220916- Mesoscale Precipitation Discussion 0556 NWS Weather Prediction Center College Park MD 1118 PM EDT Wed Jun 21 2023 Areas affected...portions of northern Florida Concerning...Heavy rainfall...Flash flooding possible Valid 220316Z - 220916Z Summary...Training thunderstorms are located mainly just offshore of the Big Bend area of north Florida, but also extend eastward to near Cross City. A conditional, yet potentially significant flash flood threat exists tonight across the discussion area. Discussion...Thunderstorms have stalled on the southern flank of a remnant MCS that moved through portions of northern Florida earlier today. The storms are oriented generally along a line from AAF to CTY and are training from west to east while also producing 2-3 inch/hr rain rates mainly over open Gulf Waters near the Big Bend/Apalachee Bay area. These storms were also located on the northern side of a 30 knot low-level jet, and a moist, buoyant airmass (characterized by 2000+ J/kg MLCAPE and 1.9 inch PW values south of the rainfall axis) was also supporting the deep convection. Fortunately, the heavier rain rates were persisting over Gulf Waters, but a few areas of 1+ inch/hr rain rates have materialized near AAF and near CTY over the past 1-2 hours. The concern with this complex is that both synoptic and mesoscale forcings for heavier precipitation will change little, while some chance of more development over land (both near AAF and from CTY to GNV) will continue over the next 3-6 hours. Models suggest that the low-level jet aiding on convective development will back slightly while maintaining its intensity (around 30 knots), providing convergence and continued storm development.=20 Additionally, westerly flow aloft (parallel to the ongoing axis of convection) will remain in place through the next 6+ hours, and persistent rainfall across the Florida Panhandle will help maintain a cold pool centered near Tallahassee for the next several hours as well. Models suggest that the eastern extent of the heavier precip could build inland toward Gainesville and perhaps Jacksonville, although storms would have to overcome a relative stable airmass with northeastward extent. Storms could also continue to backbuild over areas near Apalachicola also through 09Z.=20 Should the heavier rainfall materialize over these areas as expected, flash flooding will become increasingly possible especially across urbanized/low-lying areas. FFG thresholds are in the 3 inch/hr range, suggesting that multiple hours of heavier rainfall will likely be needed over land areas to result in a more widespread flash flood event. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-JpJL_GCEZXwuHi6e_55p2EVCR8YdKMyR1bM8vbIDZh9drW-xuv8pwfNNrUQOUOTUUSN= 8UX2rdz5XWxY2qo9xNcPldM$ for graphic product... ATTN...WFO...JAX...TAE...TBW... ATTN...RFC...SERFC...NWC... LAT...LON 30288311 30148226 29938182 29468188 29128238=20 29008356 29348508 29678560 30108548 30238506=20 30278427=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) .