Flash Flood Guidance
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Issued by NWS
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179 AWUS01 KWNH 131427 FFGMPD FLZ000-ALZ000-MSZ000-LAZ000-131826- Mesoscale Precipitation Discussion 0264 NWS Weather Prediction Center College Park MD 1027 AM EDT Mon May 13 2024 Areas affected...southeastern Louisiana, southern Mississippi, southern Alabama, Florida Panhandle Concerning...Heavy rainfall...Flash flooding likely Valid 131426Z - 131826Z Summary...Heavy rain/localized flash flooding remains likely with an elongated convective complex intensifying along/north of the I-10/12 corridor. Multiple hours of 1-2.5 inch/hr rain rates are expected in parts of the discussion area. Discussion...Convective trends indicate intensification of an ongoing MCS located from near Mobile, AL to near Hammond, LA. Mesoscale organization along sections of this MCS has enabled a subtle southward translation of the axis of heaviest rain with the complex, with 2 inch/hr rain rates now being estimated per MRMS near/north of Mobile and areas of 1-2 inch/hr rates noted near Hammond. The complex is located on the nose of robust low-level flow (20-30 knots at 850mb), and individual cores were propagating closer to strong surface-based instability (2500 J/kg MLCAPE), indicating that storms were likely becoming surface-based with time. The orientation of the MCS (parallel to flow aloft) was allowing for convective training, supporting a 2-3 hour period of 1+ inch/hr rain rates. These rates are likely to cause at least localized flash flood issues near low-lying, urbanized land surfaces. The MCS is likely to continue to produce heavy rainfall along its trek across coastal areas of LA/MS/AL and the Florida Panhandle over the next 3-5 hours. FFGs are relatively high (3-4 inch/hr thresholds) across the discussion area, further suggesting isolated flash flood potential where prolonged rainfall can fall in urban/low-lying areas. A temporary reprieve in the heavy rainfall is expected for a few hours on the western flank of the MCS, although additional rainfall is likely to develop with evolving convection well upstream (south/southwest Texas) later today/this afternoon. Cook ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...JAN...LIX...MOB...TAE... ATTN...RFC...LMRFC...SERFC...NWC... LAT...LON 31378826 31338665 30978522 30218449 29728456 29668538 29868823 29808987 30269070 30959040 31158968