Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 16 2024 14:21:51 AWUS01 KWNH 161421 FFGMPD MOZ000-MNZ000-IAZ000-KSZ000-NEZ000-SDZ000-161800- Mesoscale Precipitation Discussion 0158 NWS Weather Prediction Center College Park MD 1021 AM EDT Tue Apr 16 2024 Areas affected...eastern Nebraska, southeastern South Dakota, northeastern Kansas, northwestern Missouri, and western into central Iowa Concerning...Heavy rainfall...Flash flooding possible Valid 161420Z - 161800Z Summary...Bands of convection are resulting in prolonged rain rates (including 2+ inch/hr rates at times) across the discussion area. Areas/spots of flash flooding are possible through 18Z this morning. Discussion...Over the last hour or so, a couple of dominant convective bands have taken on a favorable orientation for training despite relatively fast steering flow and storm motions. One of these bands extended from near Yankton, SD to near Columbus, NE, with rightward-moving structured embedded and assisting in both 1 inch/hr rain rates and 2-2.5 inch/3-hr rain rates beneath the band. This area was continuing to ingest surface-based parcels due to southeasterly low-level flow and near 60F dewpoints beneath very cold air aloft (-20C at 500mb), contributing to relatively efficient rain rates. Local FFGs in the 1.5 inch/hr range were being approached on a localized basis, suggesting a continued flash flood risk as long as convection remains rooted near the surface. Some cells were moving northward toward cooler surface air, however, which may weaken storms and lower rain rates as they drift into southeastern South Dakota. Southeast of this area, a second band of more robust convection extended from near Clarinda in southwest Iowa through Topeka, KS. These cells are also training and fostering areas of nearly 2 inch/hr rain rates due to favorable orientation to south-southwest steering flow aloft. Stronger buoyancy in this area was also contributing to slightly stronger/deeper updrafts per satellite imagery. These storms were also lifting northward toward a low-level boundary and stable air across central Iowa, although ascent/forcing aloft may sustain training cells toward the Des Moines, IA area after 16Z or so. Models suggest that warm advection/destabilization will develop northward into areas of central/northwestern Iowa over time, resulting in a broader spatial opportunity for deep, training updrafts and heavy rain rates. Areas of 1-2 inch/hr rain rates are expected to approach FFG thresholds over the discussion area on at least a spotty basis through 18Z or so. The threat could persist beyond 18Z, although model trends seem to indicate a faster forward progression of convection (and less training) through the afternoon hours. This scenario will be re-evaluated for another potential MPD after 18Z. Cook ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-kw_AI6psELYJt7p5ilNmPePkESZv9PENmW_0WJLCtF-otdWC3X5Knap04LXLjS01jl7= j_G55Lxcuo3_mTOAiNCTFZc$ for graphic product... ATTN...WFO...DMX...EAX...FSD...ICT...MPX...OAX...SGF...TOP... ATTN...RFC...ABRFC...MBRFC...NCRFC...NWC... LAT...LON 44399753 44339634 43329360 41849265 39539264=20 38389370 38069443 38039543 39329568 40479675=20 42379784 43669793=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .