Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Apr 13 2023 20:01:29 AWUS01 KWNH 132001 FFGMPD FLZ000-GAZ000-140000- Mesoscale Precipitation Discussion 0184 NWS Weather Prediction Center College Park MD 401 PM EDT Thu Apr 13 2023 Areas affected...Northern Florida Coast...Far Southeast Georgia Concerning...Heavy rainfall...Flash flooding possible Valid 132000Z - 140000Z SUMMARY...Converging wind flow at the surface and low levels will provide a favorable environment for additional thunderstorms. Flash flooding is possible with urbanized corridors and poor drainage areas. DISCUSSION...Surface observations show SW winds along the western half of the Florida Peninsula is occurring at the same time synoptically driven SE flow off the coast and the developing sea breeze stalls inland off the coast. This is resulting in a strengthening axis of deep moisture convergence over coastal northern Florida. Thunderstorms have already developed, but the approaching storms could slow down and become quasi-stationary over head from the initial surface easterly flow for a few hours. SPC mesoanalysis shows as much as 1,500 J/kg of MLCAPE in the highlighted region, along with 80% RH within the LCL-EL layer. The latest HRRR shows the easterly onshore winds along the coast and resulting mean SW flow above 925mb creating an environment where surface-3km SRH values could top 100 m2/s2, as well effective bulk shear values between 25-30 knots. A couple deterring factors that keep the flash flood threat much more localized are PWs hovering around 1.5" and the strong southwesterly 850-300mb mean winds could keep cells moving fast enough to limit residency time of these cells. These storms interacting with the sea breeze front over a more densely populated area, which contains a greater concentration of hydrophobic surfaces, could result in areas of flash flooding. The combination of 1.5" PWs and 1,500 MLCAPE will coincide with warm cloud layer depths approaching 10,000 feet. There is the opportunity for these storms to generate efficient warm rainfall processes around the afternoon rush hour. Hourly rainfall rates could surpass 2"/hr, and should cells slow and reside along the sea breeze front longer, it could lead to localized amounts approaching 4". Areas most prone to flash flooding include the more urbanized corridors and in poor drainage areas where standing water could occur. Mullinax ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6MYK06Dk4HYY6YvCXrMllkHVNWza4_W114qUR5RhJoSOB3bfF0y-er4kOtIs1D6z3Jui= WtGAY0m_iSar28G8DTTtohQ$ for graphic product... ATTN...WFO...JAX...MLB... ATTN...RFC...SERFC...NWC... LAT...LON 31038159 29198096 28618054 28418097 28628153=20 29398183 30178209 30888236=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) .