Flash Flood Guidance
Issued by NWS
Issued by NWS
535 AWUS01 KWNH 101916 FFGMPD SCZ000-GAZ000-ALZ000-110100- Mesoscale Precipitation Discussion 0418 NWS Weather Prediction Center College Park MD 315 PM EDT Mon Jun 10 2024 Areas affected...Southern Georgia...Ext. Southern South Carolina... Concerning...Heavy rainfall...Flash flooding possible Valid 101915Z - 110100Z SUMMARY...Strengthening thunderstorms in ideal environment for training may pose spots of 2-4" and possible low-end incidents of flash flooding through the evening. DISCUSSION...Surface analysis and RAP analysis fields depict a well defined stationary front across southern GA with tight theta-E gradient to the north and a weaker/slightly drier area across the FL panhandle and northern FL. Solid insolation has allowed temperatures into the low 90s with Tds in the low to mid 70s while CIRA LPW denotes solid stream of mid-level moisture overlaid to support a narrow ribbon of 2-2.25" total PWATs. Additionally, northerly flow north of the front is supporting the FGEN/moisture convergence to develop cells at along the boundary; while a subtle shortwave in central GA will continue to support unidirectional flow through S GA, while also supporting weak confluent surface to 850mb flow across SE AL allowing for additional upstream redevelopment. Current EIR and RADAR show stronger development over the last hour with increased coverage in Lee to Toombs counties with 1.5"/hr rates starting to be estimated. Given the SBCAPEs of 3500-4000 J/kg and the 2"+ TPW, even modest/weak flux of 5-10kts will support 2"/hr rates and alignment should allow for training. To compound issues, propagation vectors will also align with the boundary and mean flow with some very small southward push with time. This may allow for spots of multiple rounds/hours of duration to allow for spotty 2-4" totals. While the area can support rates/totals of this range for 1-3hr FFG. Grounds are very dry in the 20-25% range through 0-40cm (about 25th percentile). The strength of rates are harder soils may reduce infiltration and increase run-off; so there remains some potential for isolated incidents of flash flooding with those highest totals in best training along this axis/frontal zone. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...CHS...FFC...JAX...TAE... ATTN...RFC...SERFC...NWC... LAT...LON 32688049 32388034 31898090 31258125 31078198 31048445 31368508 31838501 31988431 32088332 32228242 32528137