Flash Flood Guidance
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Issued by NWS
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692 AWUS01 KWNH 140635 FFGMPD FLZ000-GAZ000-ALZ000-141230- Mesoscale Precipitation Discussion 0270 NWS Weather Prediction Center College Park MD 235 AM EDT Tue May 14 2024 Areas affected...FL Panhandle into northern FL/southern GA Concerning...Heavy rainfall...Flash flooding possible Valid 140634Z - 141230Z Summary...A localized flash flood threat will continue for the FL Panhandle into northern FL/southern GA through 12Z. An additional 2-4 inches is expected in some of the same locations which picked up heavy rain over the past 24 hours. Discussion...GOES East infrared satellite and regional radar imagery at 06Z showed an MCS tracking east along the central Gulf Coast with an MCV located 70 miles SSE of Mobile Bay. While some warming of cloud tops has been observed over the past 1-2 hours, the coldest cloud tops and observed lightning strikes have been confined to along and just south of the AL/MS into the western FL Panhandle coast, co-located with a gradient in MLCAPE and quasi-stationary front. SPC mesoanalysis data from 06Z showed MLCAPE values of roughly 500-1000 J/kg across coastal regions of AL into the FL Panhandle and Big Bend region. This region also resided within the diffluent and divergent portion of a RAP estimated 110-130 kt jet max aloft centered over northern portions of the lower MS Valley. WSW low to mid-level flow should take the MCV east-northeast along a similar path as the surface front, reaching southern GA/northern FL toward 12Z. Expect the MCS to continue its forward speed of 30-40 kt with rainfall rates of 1-3 in/hr, with the upper values of that range reserved for training ahead of the MCV circulation, contained within the better instability values near the coast (through ~10Z) and eventually northern FL into southern GA as instability increases with low level moisture advection ahead of the advancing MCS. There is general consensus of this scenario in the latest hires model guidance, but recent runs of the HRRR appear to slow to progress convection downstream. Nonetheless, there may be a lowering of the flash flood threat through 12Z as the MCS approaches drier antecedent ground conditions along with a possible increased forward speed. Portions of the central Gulf Coast into the FL Panhandle, northern FL and southern GA have received roughly 2-4 inches over the past 24 hours and the addition of another 2-4 inches through 12Z may result in localized flash flooding. Otto ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...JAX...MOB...TAE...TBW... ATTN...RFC...SERFC...NWC... LAT...LON 31388164 31068127 30668132 29888123 29388271 29328454 29328539 29858687 29968761 30668748 30998638 31258416 31368242