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Flash Flood Guidance
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Issued by NWS
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771 AWUS01 KWNH 170556 FFGMPD MOZ000-ARZ000-OKZ000-KSZ000-171154- Mesoscale Precipitation Discussion 0889 NWS Weather Prediction Center College Park MD 155 AM EDT Sat Aug 17 2024 Areas affected...southeastern Kansas, northeastern Oklahoma, western/central Arkansas Concerning...Heavy rainfall...Flash flooding possible Valid 170554Z - 171154Z Summary...Flash flood potential continues as backbuilding convection continues to increase in coverage across southeastern Kansas and northeastern Oklahoma. This risk should continue through at least 12Z. Discussion...A lead convective complex has matured while forward-propagating southeastward across portions of western and central Arkansas. These storms are in a moist/unstable environment, with 1.8+ inch PW values supporting spots of 1-1.5 inch/hr rain rates despite the brevity of heavier rainfall. These rates are overspreading areas of FFG thresholds in the 3 inch/hr range, suggesting that any flash flood potential will be quite spotty/isolated and tied to sensitive/low-lying areas. Farther upstream, elevated convection has managed to redevelop along an axis extending from near Chanute, KS south-southeastward to near Talequah, OK. These storms were focused on the nose of 20-25 knot 850mb flow while also orienting parallel to northwesterly flow aloft. The orientation of this convection (along with ~2 inch PW values and near ~7C/km mid-level lapse rates) is a bit more favorable for training and spots of 1-2 inch/hr rain rates. Furthermore, this rainfall will occur over wetter ground conditions from prior rainfall from the aforementioned MCS earlier in the evening, and lower FFG thresholds (generally in the 1-2 inch/hr range) are noted. The overall pattern is a bit more favorable for flash flooding through the night especially near axes of training. Models suggest that the 850mb convergence axis will likely persist across southeastern Kansas through western Arkansas even as low-level flow veers through the early morning. Spots of 1-2 inch/hr rain rates are expected to continue through 12Z. Isolated 3-4 inch rainfall totals are possible in this regime. Cook ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...ICT...LZK...SGF...SHV...TOP...TSA... ATTN...RFC...ABRFC...LMRFC...MBRFC...NWC... LAT...LON 38309689 37989506 36359297 34899223 33559323 33919488 36619659