Flash Flood Guidance
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Issued by NWS
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779 AWUS01 KWNH 311645 FFGMPD MSZ000-LAZ000-312244- Mesoscale Precipitation Discussion 0359 NWS Weather Prediction Center College Park MD 1245 PM EDT Fri May 31 2024 Areas affected...southern Louisiana, southern/coastal Mississippi Concerning...Heavy rainfall...Flash flooding possible Valid 311644Z - 312244Z Summary...Scattered, slow-moving convection will result in several areas of 1.5-3 inch/hr rain rates at times through at least 22Z. Flash flooding is possible in this regime. Discussion...Over the past hour, the leading edge of a mature MCS has crossed into southwestern Louisiana per radar mosaic imagery. The MCS was making modest eastward progress (generally at around 35 knots or so) while producing spots of 1-2 inch/hr rain rates (estimated per MRMS). Additionally over the past hour, additional convection has developed along and ahead of this MCS across much of southern Louisiana. That newer convection was drifting northward while producing additional 1-2 inch/hr rain rates at times. The rain rates exhibited by this activity is supported by a buoyant, moist airmass characterized by ~2000 J/kg MLCAPE and 1.5+ inch PW values, respectively. Both cells and the leading edge of the MCS are likely to support local/isolated areas of prolonged rain rates, with potential for 3 inch/hr rates at times. Additionally, the presence of a low-level boundary (subjectively analyzed along the I-10/12 corridor) will likely aid in supporting MCS persistence across the southern half of Louisiana today. The rates are likely to fall in areas that have experienced excessive rainfall over the past month. With wet soils and local/urban areas susceptible to runoff, at least a few instances of flash flooding are expected today. 2-3 inch/hr FFG thresholds should be approached on at least a spotty/isolated to scattered basis. The MCS will likely reach the Lafayette, LA area through 1830-1930Z and portions of the Baton Rouge/New Orleans Metro areas after 20Z. Cook ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...JAN...LCH...LIX...MOB...SHV... ATTN...RFC...LMRFC...WGRFC...NWC... LAT...LON 31609011 30668910 29508893 28858946 29059190 29649367 31089346 31469255