Flash Flood Guidance
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Issued by NWS
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490 AWUS01 KWNH 311937 FFGMPD MNZ000-IAZ000-NEZ000-SDZ000-010130- Mesoscale Precipitation Discussion 0360 NWS Weather Prediction Center College Park MD 336 PM EDT Fri May 31 2024 Areas affected...Northeastern Nebraska through Southwest Minnesota Concerning...Heavy rainfall...Flash flooding possible Valid 311936Z - 010130Z SUMMARY...Multiple forcing mechanisms causing widely scattered storms capable of producing up to 3 inch per hour rainfall rates. Flash flooding possible in flood-sensitive areas. DISCUSSION...Moisture advecting northwestward at the nose of a low level jet originating in the Gulf is colliding with a surface cold front, mid-level deformation zone, and upper level shortwave over Nebraska to result in an area of very slow moving storms that have a history of producing rainfall rates to 3 inches per hour. The area has some sensitivity to flooding with soil moisture levels at or a little above average for this time of year. FFGs in much of the highlighted region are below 2 inches in an hour and 2.5 inches in 3 hours. PWATS are above 1.5 inches in most of the region and SPC Mesoanalysis shows max surface based cape as high as 2,000 J/kg over western Iowa. Steering flow in the vicinity of the front is weak due to the presence of the mid-level deformation. The area of rain with embedded slow moving convection is expected to expand upscale into a more well defined boundary, with convection developing and riding northeast along it. The congealing of multiple areas of storms may result in steadier rainfall, but the peak rainfall rates of in embedded convection may decline a bit as a result. Flash flooding will be possible in any areas where the storms are slow moving or localized areas of training convection develop. The upper level shortwave moving across the area will serve as the "back edge" of the convection, shifting everything north and east and weakening with time with loss of solar heating after 00Z. Wegman ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...GID...LBF...MPX...OAX... ATTN...RFC...MBRFC...NCRFC...NWC... LAT...LON 44559553 44549447 43669420 42399501 41199700 40469800 41539885 42709832 43899707 44549554