Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 02 2023 19:08:22 AWUS01 KWNH 021908 FFGMPD FLZ000-030100- Mesoscale Precipitation Discussion 0839 NWS Weather Prediction Center College Park MD 307 PM EDT Wed Aug 02 2023 Areas affected...Western Florida Peninsula Concerning...Heavy rainfall...Flash flooding possible Valid 021907Z - 030100Z Summary...Slow moving showers and thunderstorms will continue to increase across the Florida Peninsula today and drift S/SW through the evening. Rainfall rates of 2-3"/hr are likely, which could result in 3-5" of rain, with locally higher amounts. Flash flooding is possible. Discussion...The regional radar mosaic this aftn shows increasingly widespread showers and thunderstorms across the southern 2/3 of the Florida Peninsula. These storms are developing within extremely favorable thermodynamics characterized by PWs above 2 inches and SBCAPE as high as 4000 J/kg according to the SPC RAP analysis. While deep layer ascent is weak, convergence along the Atlantic sea breeze and west coast Gulf breeze is producing locally enhanced ascent to drive convective development. Additional storms are occurring along outflow boundaries and storm mergers as minimal bulk shear continues to support primarily pulse convection. Rainfall rates within these thunderstorms has been estimated via KTBW radar to be above 2"/hr, resulting in some mesonet observations above 1.5" of rain already today. As the aftn progresses, the Atlantic sea breeze is likely to merge with the Gulf breeze along the Sun Coast to focus convection. At the same time, persistent E/NE low-level flow advects even greater moisture into the column with PWs forecast to reach 2.25" later today as some residual mid-level dry air saturates. This will not only yield intensifying storms with rain rates above 3"/hr as reflected by HREF neighborhood probabilities, but also result in storms that become nearly stationary. While the greatest concentration of slow moving convection is expected along this boundary, other development is likely through additional storm mergers/outflow interactions as bulk shear remains weak. Any of these intense cells could produce sub-hourly rainfall rates above 4"/hr, as the HRRR suggests some 15-min rainfall may exceed 1". This will likely result in 3-5" of rainfall with locally higher amounts possible noted by HREF neighborhood probabilities for 5" reaching 30-40%. Recent rainfall across the western peninsula has been generally below normal as noted by 7-day AHPS rainfall that is 25-75 percent of normal. This is resulting in high FFG and well below normal USGS streamflow anomalies, reducing the overall flash flood threat. However, the extremely slow motion of these storms and intense rain rates still will support at least isolated instances of flash flooding, especially over urban areas or beneath the most impressive storm collisions. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!8lsYVxdJeblqTr7os69Lv-l6_2gxb1UB-PrHqs8oG_TUoR5-XYxMEmZS9woETKXH3vcK= 30x5sGF-dSPXmoBd8YpKBYA$ for graphic product... ATTN...WFO...MFL...MLB...TBW... ATTN...RFC...SERFC...NWC... LAT...LON 28968272 28888221 28298180 27628138 27118111=20 26618077 26178073 25948086 25768131 25788164=20 26128206 27188263 28048285=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) .