Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 28 2025 01:35:16 AWUS01 KWNH 280134 FFGMPD MNZ000-SDZ000-NDZ000-280700- Mesoscale Precipitation Discussion 0536 NWS Weather Prediction Center College Park MD 933 PM EDT Fri Jun 27 2025 Areas affected...Eastern and Central North Dakota Concerning...Heavy rainfall...Flash flooding possible Valid 280132Z - 280700Z Summary...Supercells blossoming over North Dakota will steadily intensify and grow upscale tonight. This convection will contain rainfall rates that could exceed 2"/hr at times, leading to stripes of 1-3" of rainfall. Flash flooding is possible. Discussion...The regional radar mosaic combined with the GLM flash extent density product this evening shows a rapid uptick of both coverage and intensity of thunderstorms across central North Dakota. This activity is strengthening in response to increasing ascent downstream of a shortwave moving out of western North Dakota with additional ascent provided via the LFQ of a modest upper jet streak and the slow increase in convergence along the nose of the 850mb LLJ. This LLJ is still modest, measured via VWPs across South Dakota at 20-25 kts from the south, but should steadily climb the next several hours to 30-40 kts. This will not only increase ascent, but also draw more impressive thermodynamics northward as PWs surge to 1.75 inches and coincident with MUCAPE surging to 3000 J/kg. This evolution downstream of the developing thunderstorms should promote an environment to support rapid growth and organization across central and eastern North Dakota. As the LLJ ramps up to improve the thermodynamics, it will additionally increase shear to 40-50 kts to support both supercells and potentially an MCS. Although mean 0-6km winds are likely to remain progressive to the east at 25-35 kts, aligned Corfidi vectors suggest training is likely, especially along the typical SW flanks and outflows as convection shifts east and the LLJ veers subtly more to the SW. These intense thermodynamics will support rainfall rates for which the HREF indicates has a 10-20% chance of exceeding 2"/hr, from which the HRRR suggests 15-min rainfall could reach as high as 1" (brief 4"/hr rates) despite the progressive nature of convection. While the general fast motion of cells, at least in the next few hours, should offset some of the flash flood potential, these intense rainfall rates could still cause rapid runoff. This will be most likely along any short-term training boundaries where event total rainfall in the next several hours could be 1-3 inches, and 3-hr FFG exceedance probabilities peak above 25%. Despite the uncertainty in the exact evolution reflected by variability in the CAMs, the environment will become increasingly supportive of these intense rates and short-term training, which atop the modest FFG could result in flash flooding instances overnight. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6imsz0UVU6e2GLkHqa_f8DPW8yE6g9adHf6pBTrrtoSASPWdTQsOThtIR5T6DEShzse3= xCmd6IW_KBPPyIq5bg-WwpY$ for graphic product... ATTN...WFO...ABR...BIS...FGF... ATTN...RFC...KRF...MSR...NWC... LAT...LON 48589836 48129668 47459642 46639687 45959777=20 45859935 46530097 47210168 47530175 47970146=20 48060133 48510027=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) .