ACUS11 KWNS 202314
SWOMCD
SPC MCD 202314=20
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 https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-ZcPjHvo7SANViDA6yVST4dPeSnjbrOEf8wNA2_3kujerCxLZ3YHD9EqPEkFRd019tOa1MlgN= _jTWVbkoqlbBl-EElk$ 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=20

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


=3D =3D =3D
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