Subj : MESO: Mesoscale Discussion 1320 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 17 2025 00:17:17 ACUS11 KWNS 170017 SWOMCD SPC MCD 170016=20 IAZ000-NEZ000-KSZ000-COZ000-170145- Mesoscale Discussion 1320 NWS Storm Prediction Center Norman OK 0716 PM CDT Mon Jun 16 2025 Areas affected...much of Nebraska...far northwest Kansas and western/central Iowa Concerning...Severe Thunderstorm Watch 424... Valid 170016Z - 170145Z The severe weather threat for Severe Thunderstorm Watch 424 continues. SUMMARY...Rapid thunderstorm development is ongoing across portions of central and western Nebraska. Very large hail and damaging winds will be possible. A tornado or two may also be possible early in the thunderstorm life cycle. The severe threat will continue through the evening. DISCUSSION...Rapid thunderstorm development is underway across portions of central Nebraska within a maximum of extreme most-unstable CAPE (greater than 5000 J/kg). Additional thunderstorms are quickly developing across northwest Kansas within a strongly unstable and sheared environment as well. Expectation is for additional thunderstorms to continue to develop and rapidly intensify across central and southern Nebraska this evening along and near a southward moving frontal boundary. Given the extreme instability in place, and effective-layer shear greater than 35 knots, very large hail (potentially exceeding 4 inches) and damaging winds (potentially greater than 65 knots), will be possible any severe thunderstorm. Given the degree of instability, a low-level vorticity reservoir within the frontal zone, and a wind profile supportive of supercells, a tornado or two cannot be ruled out, especially early in the thunderstorm evolution when storms remain more discrete. Given the expected explosive development and increasing number of storms, upscale growth into one or more linear segments should occur. As this occurs, a transition away from very large hail toward widespread wind threat should occur. With time, these linear MCSs should move south into Kansas continuing the severe wind threat. Farther east, across the east portions of Severe Thunderstorm Watch #424, an organized linear MCS continues to move south across the Nebraska-Iowa border. The environment across central and eastern Iowa is less conducive for severe given lower instability and weaker shear, so a overall weakening trend would be expected in the next couple of hours. The western portion of this MCS should continue to develop westward with time, eventually merging with the developing thunderstorms across central and western Nebraska. ...Marsh.. 06/17/2025 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9hsu6piqqEboOiWtp48-Vfbv017lynogrA9TzZwCFwB4WX6UhHDLIZ626NMEXq6hR732WU0Hu= yVwYP4RXMHLYV_Pgpg$ for graphic product... ATTN...WFO...DMX...FSD...OAX...GID...LBF...GLD...BOU...CYS... LAT...LON 40430263 41960265 41970198 42100196 42080017 42820013 42699952 42899896 42719830 42449830 42439735 42379734 42349701 42279701 42269669 42279631 42219632 42219528 42569534 42569493 43239485 43259449 42929442 42919357 42229346 42229368 41879370 41889385 41189384 41169439 40909447 40899580 40809582 40789642 40519645 40529692 40679694 40679778 40339783 40349920 40039919 40009905 39579904 39550203 40400204 40430263=20 MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...2.75-4.25 IN =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) .