Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 27 2025 18:41:45 AWUS01 KWNH 271841 FFGMPD FLZ000-280045- Mesoscale Precipitation Discussion 0531 NWS Weather Prediction Center College Park MD 241 PM EDT Fri Jun 27 2025 Areas affected...Florida Peninsula Concerning...Heavy rainfall...Flash flooding possible Valid 271845Z - 280045Z Summary...Slow moving thunderstorms along the sea breeze boundary will drift slowly westward or stall through the evening. Rainfall rates of 2-3+"/hr are likely, which could result in isolated rainfall amounts approaching 5". Isolated flash flooding is possible. Discussion...The regional radar mosaic this afternoon shows widespread showers and thunderstorms ongoing along the east coast of the Florida Peninsula. These storms are blossoming within impressive thermodynamics characterized by SBCAPE of 3000-5000 J/kg overlapped with PWs above 2 inches. Although deep layer ascent is modest beneath an upper ridge, convergence along this sea breeze will continue to force updrafts to drive convection, with additional storms developing along outflows and storm mergers within a region of weak 0-6km bulk shear. Radar-estimated rainfall rates from KMLB have been as high as 2"/hr already this aftn, but storm lifetimes have been short in the pulse environment. This is likely to remain the evolution through tonight, but guidance indicates that a plume of enhanced bulk shear may spread into eastern FL this evening, helping to force at least modest storm organization as outflows and storm mergers occur. This could enhance the duration of heavy rainfall in a few areas as clusters move chaotically across the region due to the offsetting motion between the westward advancing sea breeze and mean S/SW 0-6km wind. With rainfall rates forecast by both the HREF and REFS to have a moderate chance (40-60%) of exceeding 2"/hr, and the HRRR 15-min rainfall indicates up to 1" at times (short duration 4"/hr rainfall), these slow motions could produce 2-4" of rain with higher amounts above 5" possible (10-20% chance) in isolated locations. There remains uncertainty into exactly where the heaviest rain will occur through this evening, but the pinned sea breeze and resultant clusters of storms should force the focus to be from the Space Coast southward as shown by HREF and REFS PMM, and supported by the synoptic flow. While FFG is high across the area, should any of these storms stall across the urban east coast, instances of flash flooding could result. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6OhYw0UuIKzzosHS_vuSFQyotQ3x8U_v3PGqXJG0XXBnjiv6SHB_7E0ME90OhGvOzZp1= jV55Kr030FeoCFfoZ1T4m3E$ for graphic product... ATTN...WFO...JAX...MFL...MLB...TBW... ATTN...RFC...ALR...NWC... LAT...LON 29348116 29138085 28498036 28018026 26847986=20 26187995 25658018 25488036 25618048 25948073=20 26408098 26958121 27648140 28348149 28998140=20 =20=20=20=20=20=20=20=20=20=20=20=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) .