ZCZC SPCSWOMCD ALL ACUS11 KWNS 202314 SPC MCD 202314 SDZ000-NDZ000-MTZ000-210045- Mesoscale Discussion 1384 NWS Storm Prediction Center Norman OK 0614 PM CDT Fri Jun 20 2025 Areas affected...portions of southeastern Montana...southwestern North Dakota...far northwest South Dakota Concerning...Severe Thunderstorm Watch 447... Valid 202314Z - 210045Z The severe weather threat for Severe Thunderstorm Watch 447 continues. SUMMARY...Severe wind and hail will accompany ongoing supercells and multicells over the next few hours. Upscale growth into an MCS may eventually occur. Should this occur, conditions are favorable for bow-echo development with a high-end severe wind threat. DISCUSSION...A band of multicells and supercells continues to track eastward across far southeastern Montana, atop an unstable boundary layer and strong vertical wind shear. 22Z mesoanalysis and a special 2055Z ICECHIP sounding depict well over 1000 J/kg MLCAPE, with large, curved, and elongated hodographs supporting around or over 50 kts of effective bulk shear with 250+ effective SRH. Ahead of these storms, low-level moisture increases substantially, especially around central ND, where mesoanalysis depicts well over 2000 J/kg MLCAPE. As such, the ongoing storms should continue eastward with a threat for severe wind and hail in the short-term. A tornado is also possible with any discrete supercells given strong low-level shear, especially after 01Z, when the storms are poised to move into better low-level moisture. It is unclear if and/or when these storms merge cold pools and grow upscale into a singular MCS. Surface observations and mesoanalysis depict multiple surface and/or low-level boundaries in place that may aid in upscale growth. However, a plethora of earlier and recent CAM guidance diverges in their solutions regarding later evolution of ongoing storms. Some members show storms remaining as supercells, with others depicting the development of an MCS. Should the later scenario occur, the very steep mid-level lapse rates and aforementioned vertical shear profile would highly support bow echo development with efficient severe wind production, including the possibility of multiple 75+ mph wind gusts. ..Squitieri.. 06/20/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...BIS...UNR...BYZ...GGW... LAT...LON 45740496 46500520 46920516 47380457 47500387 47420204 46820095 45960068 45540137 45350236 45250333 45170388 45170431 45740496 MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH MOST PROBABLE PEAK WIND GUST...75-90 MPH MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN NNNN