Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Mar 22 2024 17:54:10 AWUS01 KWNH 221754 FFGMPD FLZ000-222200- Mesoscale Precipitation Discussion 0107 NWS Weather Prediction Center College Park MD 153 PM EDT Fri Mar 22 2024 Areas affected...FL Keys into southeastern FL Concerning...Heavy rainfall...Flash flooding possible Valid 221752Z - 222200Z Summary...An increased risk of localized flash flooding will exist across the FL Keys into southeastern FL over the next few hours. Hourly rainfall totals of 1-2 inches will be possible, but cannot rule out isolated rates over 2 in/hr where favorable instability/forcing overlap. Discussion...Regional radar and visible satellite imagery showed an MCS extending from offshore of southwestern FL into the southern Peninsula with an embedded circulation/low located over the southern Everglades at 1730Z. An outflow enhanced effective front extended southwestward from the low over the open water and southeastward through the Upper Keys with surface dewpoints in the upper 60s across the region near and south of the boundary. Precipitable water values were 1.6 to 1.8 inches from the 12Z MFL and KEY soundings which displayed high relative humidity throughout the column and freezing levels of 12.5 to 14.0 kft. Therefore, the environment was supportive of efficient rainfall production despite relatively low instbility; the 500+ J/kg MLCAPE contour only covering the Keys, with lower values to the north. Rainfall over the past 3-4 hours has resulted in 0.5 to almost 2 inches of rain in the southern Miami suburbs with hourly totals near 1 inch over the past 1-2 hours. Moderate (~20-30 kt) low level warm advection ahead of the meso-low will continue to allow for steady moderate to locally heavy rain across the urban southeastern corridor over the next few hours as it tracks southeastward, in addition to general overrunning of the boundary in place just south of the region. The greatest focus for higher rainfall intensities will exist just ahead of the meso-low with possible training of heavy rain from west to east mostly over the Everglades but the expected axis of training may clip the the southeastern urban corridor as well, with 1 to 2+ in/hr. Embedded convective elements will locally increase hourly rainfall over 1 inch elsewhere across the region with additional totals of 1-3 inches possible through 22Z. Farther south where instability is a bit higher, greater potential will exist for hourly rainfall of 1-2 inches, with locally higher rates possible but the progressive southeastward movement of the MCS should limit short term additional rainfall totals with this initial round of storms across much of the Keys. However, additional rounds of heavy rain are expected later this evening with additional MPDs possible. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!7u0RUM5dWSArTYdVdT8glsrXghbqbqLJMBCw0ffpIvQEB_pX94kcBvD7MKE1ysS0h9Ie= KTNJrFTcY35H0PSTwp5Py2I$ for graphic product... ATTN...WFO...KEY...MFL... ATTN...RFC...SERFC...NWC... LAT...LON 26478041 26417988 25667990 24818047 24378135=20 24448195 24698202 25128196 25558136=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) .