Flash Flood Guidance
Issued by NWS
Issued by NWS
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014 AWUS01 KWNH 241837 FFGMPD INZ000-ILZ000-MOZ000-242330- Mesoscale Precipitation Discussion 0316 NWS Weather Prediction Center College Park MD 237 PM EDT Fri May 24 2024 Areas affected...Eastern MO...Central IL...Western IN Concerning...Heavy rainfall...Flash flooding possible Valid 241835Z - 242330Z SUMMARY...Ongoing moisture advection oriented perpendicular to a stalled convergence boundary will likely spawn additional thunderstorms for several more hours. Flash flooding is possible this afternoon, especially in areas hit with repeated rounds of thunderstorm activity. DISCUSSION...18Z surface analysis shows a narrow convergence axis orient W-E from northern MO and central IL into western IN. At 850mb an influx of theta-e ensued along with an increasingly unstable environment. RAP mesoanalysis shows as much as 2,000-3,000 J/kg of MLCAPE along the southern periphery of thunderstorms that have flared up along the surface trough. RAP forecasts suggest that the 850mb flow overrunning this boundary is likely to continue for several more hours, while at the same time, the flow will overrun the ensuing cold pool that will further enhance additional thunderstorm development. The 17Z HRRR shows the potential for back-building convection north of St. Louis that could result in excessive rainfall rates up to 2"/hr. While soundings will also likely contain hail, the environment based on effective bulk shear (40-50 kts) and effective SRH (100-200 m2/s2), suggest mesocyclones could help to enhance precipitation rates as well. This setup makes it ideal for congealing clusters of storms to potential train and/or back-build for several hours. 1-hr FFGs are as low as 1.5-2.0", which are within reach for the excessive rainfall rates these storms can produce. As a result, flash flooding is possible this afternoon with low lying areas and more urbanized communities particularly more susceptible to flash flooding. Mullinax ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...DVN...ILX...IND...LOT...LSX... ATTN...RFC...MBRFC...NCRFC...OHRFC...NWC... LAT...LON 40738745 39548738 38808806 38459020 38649160 39429191 40099186 40509119 40638921