Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 25 2025 16:54:46 AWUS01 KWNH 251654 FFGMPD WIZ000-MNZ000-IAZ000-SDZ000-252300- Mesoscale Precipitation Discussion 0513 NWS Weather Prediction Center College Park MD 1254 PM EDT Wed Jun 25 2025 Areas affected...northern IA, eastern SD, southern MN Concerning...Heavy rainfall...Flash flooding possible Valid 251700Z - 252300Z Summary...Showers and thunderstorms will gradually expand in coverage through the afternoon and intensify to support rain rates of 1-2"/hr. This could produce 2-3" of rain with locally higher amounts across wet antecedent soils. Flash flooding is possible. Discussion...The regional radar mosaic this afternoon shows an expansive area of stratiform rain across Minnesota. This precipitation is occurring in response to pronounced ascent within the RRQ of a strong jet streak to the northeast and persistent warm advection and isentropic ascent along the 850mb inflow axis. PWs across the region are impressive, analyzed by the SPC RAP to be 1.5 to 2.0 inches, with the limiting factor to rainfall intensity so far being the sharp instability gradient as SBCAPE above 250 J/kg is confined to areas south of the analyzed warm front. In general, the rainfall this morning has been of moderate intensity, but a few regions of training across IA, MN, and SD have resulted in 12-hr MRMS rainfall as much as 3-4 inches and saturated soils. During the next few hours, a wave of low pressure developing along the warm front will track northeast, leading to acceleration of the downstream low-level wind field. This will result in 850mb winds surging to 30-35 kts, forcing more pronounced isentropic ascent as the warm front lifts northward in response. At the same time, this will draw more intense thermodynamics northward, with PWs above 2 inches (a daily record if measured) and MUCAPE above 1000 J/kg reaching as far north as the Twin Cities this evening. This will allow for a rapid expansion of convection as reflected by high res CAMs simulated reflectivity, and in this robust environment both the HREF and REFS suggest a high probability (60-70%) of rainfall rates exceeding 1"/hr, with 15-min rainfall from the HRRR potentially accumulating to 0.5 - 0.75 inches (brief 3"/hr rates). Although 0-6km mean winds will remain progressive at 20-25 kts, Corfidi vectors aligned to the warm front could produce 2-3 inches of rain, with locally higher amounts above 4 inches possible. Rainfall already this morning, as noted above, has been locally 3-4 inches, with widespread 0.5-1 inch also measured via MRMS. This has saturated the top soils across most of the area according to the HRRR, likely lowering FFG even beyond the analyzed 1-2"/3hrs. Even in areas that have not been as saturated, HREF 3-hr exceedance probabilities reach 20-30%, further suggestive of the increasing flash flood risk into this evening. However, the greatest potential for impacts will be across urban areas or beneath any longer-term training. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6Pg2UHEt3tlvhorApDLJ_LaL9xiX2f_7IFT-UYoPJjsR8ng3iEJXj1MXcQzROIt5EryC= 9XEs1PvDxXJ2V1UN8dulnpY$ for graphic product... ATTN...WFO...ABR...ARX...DLH...DMX...FSD...MPX... ATTN...RFC...KRF...MSR...NWC... LAT...LON 45749319 45419178 44879111 44159113 43839138=20 43339206 42759358 42599531 42819665 43359770=20 43919788 44539711 44879628 45339504=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) .