Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 23 2025 21:46:46 AWUS01 KWNH 232146 FFGMPD MNZ000-IAZ000-NEZ000-SDZ000-240300- Mesoscale Precipitation Discussion 0786 NWS Weather Prediction Center College Park MD 545 PM EDT Wed Jul 23 2025 Areas affected...Nebraska through southern Minnesota Concerning...Heavy rainfall...Flash flooding possible Valid 232143Z - 240300Z Summary...Showers and thunderstorms will rapidly expand and intensify across the Central Plains and Upper Midwest this afternoon. Rainfall rates of 1-3"/hr are likely, which through training could produce 2-4" of rain with locally higher amounts. Flash flooding is likely. Discussion....The regional radar mosaic this afternoon shows rapid growth of thunderstorms from SW Nebraska through northern Iowa. These thunderstorms are blossoming in response to increasingly impressive ascent driven by a combination of height falls downstream of a trough axis approaching from the west, and intense low-level convergence along a cold front and pre-frontal surface trough. Low-level inflow on 850mb winds observed via local VWPs are surging out of the S/SW at 20-25 kts, drawing extreme thermodynamics characterized by PWs of 1.6-1.9 inches and MLCAPE as high as 4000 J/kg northward into the front. Weak waves of low pressure moving along the front are also helping to locally accelerate the flow, resulting in intense convergence for ascent. The result of this increasing lift into the intense thermodynamics has been the rapid growth of updrafts/thunderstorms, leading to MRMS measured 1-hr rainfall as much as 2.5" in discrete cells over Nebraska. The CAMs are actually well aligned for the next several hours, leading to higher confidence in evolution despite activity being slightly more widespread currently than progs would suggest. As the LLJ continues to increase towards 30 kts, it will maintain the favorable resupply of thermodynamics to support intense thunderstorm development. With PWs above the 90th percentile, the locally backed low-level flow into the front should help sustain and redevelop convection, even as individual cells move progressively on 0-6km mean winds of 15-20 kts. Additionally, with bulk shear increasing to 25-30 kts, some organization into clusters is also expected, and Corfidi vectors collapse to around 5 kts indicating slow net storm motions indicative of backbuilding into the greater instability. This is already occurring on current radar across Nebraska, leading to higher confidence in this evolution the next few hours. This could result in rainfall of 2-4" with locally higher amounts of 5" possible as reflected by both HREF and REFS probabilities due to rainfall rates that will at times reach 2-3"/hr (potentially briefly above 4"/hr). The soils across the area are generally dry as reflected by NASA SPoRT 0-10cm soil moisture that is below normal (around the 20th percentile), leading to FFG that is around 1.5" (2.5") in 1-hr (3-hrs). Despite that, HREF 3-hr exceedance probabilities reach above 40% this evening, further indicative of the intensity of the rainfall expected along this boundary. This additionally suggests the likelihood of flash flooding through the evening as slow moving storms train with these intense rain rates. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!94HF1ESiWrP9nIKqW4v1EqI1l46-MQxVVUs3RgGUGq33ELkynPWA5EnRji5x-RGu4o46= Ygzmisbk6kwwZTJlj42PGH4$ for graphic product... ATTN...WFO...ARX...DMX...FSD...GID...LBF...MPX...OAX... ATTN...RFC...KRF...MSR...NWC... LAT...LON 44389538 44359402 43819245 43499259 43079327=20 42579425 42039532 41889567 41409639 41059706=20 40739780 40549828 40469925 40559995 40630054=20 40760083 41200059 41749988 42479891 43669733=20 44119648 44279602=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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .