Subj : MESO: Mesoscale Discussion 1271 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 13 2025 17:46:48 ACUS11 KWNS 131745 SWOMCD SPC MCD 131745=20 MTZ000-131945- Mesoscale Discussion 1271 NWS Storm Prediction Center Norman OK 1245 PM CDT Fri Jun 13 2025 Areas affected...Central into Eastern/Southeastern MT Concerning...Severe potential...Watch likely=20 Valid 131745Z - 131945Z Probability of Watch Issuance...80 percent SUMMARY...Increasing thunderstorm coverage is expected across central and eastern/southeastern MT this afternoon. Large to very large hail and strong gusts are possible with these storms. DISCUSSION...Despite relatively modest temperatures, still in the mid/upper 60s, and low-level moisture, with dewpoints in the low to mid 50s, the airmass is quickly destabilizing across central and eastern MT. This destabilization is supported predominantly by cooling mid-level temperatures, which are already -11 to -15 deg C at 500 mb across the region. Southwesterly mid-level flow is expected to gradually strengthen throughout the day as a shortwave trough progresses across the Pacific Northwest into the region. The strengthening flow will contribute to orographic ascent across the higher terrain, with large-scale lift also increasing ahead of the approaching shortwave. Resulting combination of lift and destabilization is expected to foster widespread thunderstorms across the region.=20 Overall buoyancy is expected to remain relatively modest across central MT, while increasing slightly with southeasterly extent where better low-level moisture exists. Even so, there is enough buoyancy for strong updrafts, particularly when combined with the moderate to strong deep-layer vertical shear in place. Storms will likely persist off the terrain into more of the High Plains. The strong deep-layer shear will favor large to very large hail, with some hail greater than 2 inches in diameter possible. Strong and damaging outflow gusts that could reach or exceed 75 mph are also possible. Overall, the tornado risk is low, but greater low-level moisture and stronger southeasterly flow across eastern/southeastern MT suggests there is a relatively higher risk there than areas farther west. ...Mosier/Thompson.. 06/13/2025 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9FriOs_kmoJ-bnWYhtdRxiQk_5Sc0UkoWyPHa6kY12vjxC2ePuaVfZJpKv-IkWqE_WZxSsJa7= o9tZfmMLjrCeyPeUNE$ for graphic product... ATTN...WFO...BYZ...GGW...TFX...MSO... LAT...LON 46561316 47741128 48340707 47790545 46220535 45250752 45321281 46561316=20 MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 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) .