Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 02 2025 21:45:44 AWUS01 KWNH 022145 FFGMPD MNZ000-IAZ000-NEZ000-SDZ000-COZ000-030330- Mesoscale Precipitation Discussion 0346 NWS Weather Prediction Center College Park MD 545 PM EDT Mon Jun 02 2025 Areas affected...Southwest to Northeast NEB...Far Northeast CO...Northwest IA...Far Southeast SD...Southwest MN... Concerning...Heavy rainfall...Flash flooding likely Valid 022145Z - 030330Z SUMMARY...Very strong, initially very slow moving thunderstorms with potential of upstream redevelopment/repeating may result in localized clusters of 3-4" totals and likely to result in incidents of flash flooding if outside of the Sand Hills. DISCUSSION...GOES-E Visible imagery shows a narrow channel of developing cumulus along and south of a well defined cold front extending from a surface low in western MN near AQP, southward toward the IA/MN/SDak state line before angling back southwest across the eastern side of the Nebraska Sand Hills before intersecting with another developing low in far northeast CO.=20 This cu field denotes fairly impressive conditionally unstable ribbon of enhanced theta-E air with fairly rich low to mid-level moisture. MLCAPEs have risen to 2500-3000 J/kg from the low in MN toward southwest NEB, with sfc Tds pooled from mid-50s to low 60s. CIRA LPW and instability field also notes strong southerly LLJ and moisture/instability axis intersecting the frontal zone ahead of the CO low across Western KS to help feed thunderstorms into a convective complex later this evening.=20=20 A strong, compact shortwave along the southeast edge of the larger broader synoptic scale trof that is dominant over the Northern High Plains, triggered stronger severe thunderstorms and a maturing cluster, small convective complex over west-central MN.=20 Forward propagation of the complex will limit overall rainfall totals with cells, but in exiting the shortwave further stretches the 500-1000mb thickness ridge along the frontal zone. Solid moisture convergence/confluence along the front will increase and moisture convergence will start breaking out individual cells from northeast to southwest along the instability axis, as noted with a stronger initial cell entering NW IA at this time. The strong updrafts given surface to 850mb winds of 15-20kts and moisture of 1.5"/hr will allow for efficient rainfall production along with some hail initially. As the thickness ridge further elongates, propagation vectors will continue to be less than 5-10kts and within a col of weakening mid-level flow...cell motions may be very slow initially, especially further southwest into northeast and central NEB. As such, cells may start to cluster and broaden in width, with rates of 1.5-2"/hr likely becoming more numerous between 23-01z.=20 Stronger more orthogonal intersection upstream may result in greater efficiency there, but will eventually forward propagate eastward with better than normal steering flow orientation to result in some repeating. As such, localized pockets of enhanced rainfall totals along and south of the front may reach 3-4" with perhaps a very isolated 5" total occurring with best training/cell mergers. Hourly FFG along the southern and eastern edges of the Sand Hills and across into SW MN range from 1.5"/hr to 2-2.5"/3hrs. These values are likely to be exceeded in these local smaller cluster/pockets from 00-03z, with HREF neighborhood probability over 40-50% for 3" and even some 10-15% for 5". While most areas in the MPD area of concern will not receive these totals, it is likely to see a few incidents of flash flooding occurring, especially outside of the Sand Hills proper. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6I7nw_l2mITelr4EzVcLD1q_KhNMIiqnbtX44vkQrh1b9DalNoWo0IkTgQ8gmzuzEesv= LjAkGbybdgN-h2oioXjx_Mk$ for graphic product... ATTN...WFO...BOU...FSD...GID...GLD...LBF...MPX...OAX... ATTN...RFC...KRF...MSR...NWC... LAT...LON 45109515 45019441 44419418 43549489 42189605=20 41249743 40779851 40200038 40270231 41080248=20 41650102 42109934 43149700 44179609 44939584=20 =20=20=20=20=20=20=20=20=20=20=20=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) .