ACUS11 KWNS 272316
SWOMCD
SPC MCD 272315=20
NDZ000-SDZ000-MTZ000-280115-

Mesoscale Discussion 1356
NWS Storm Prediction Center Norman OK
0615 PM CDT Sat Jun 27 2026

Areas affected...parts of eastern Montana into the western Dakotas

Concerning...Severe Thunderstorm Watch 405...408...

Valid 272315Z - 280115Z

The severe weather threat for Severe Thunderstorm Watch 405, 408
continues.

SUMMARY...Storms posing a risk for large hail and localized
downbursts will transition to primarily broader swaths of strong to
severe wind gusts through 6-8 PM MDT.

DISCUSSION...Forcing for ascent associated with one or two short
wave impulses pivoting around the eastern periphery of the
large-scale upstream low continues to support increasing
thunderstorm development off the higher terrain and within the lee
surface troughing. This includes a couple of notable clusters
spreading north and northeast of the Big Horns and one progressing
across the northeastern international border area. Strongest
boundary-layer instability is focused in higher moisture content to
the east of the surface trough axis, but modestly moist upslope flow
to the west of the trough axis appears unstable enough to maintain
upscale growth during the next few hours.

Gradually, the severe hail and localized damaging downburst threat
will shift to primarily a broader strong to severe gust threat with
enlarging, strengthening and consolidating surface cold pools, which
should tend to surge east-northeastward toward the western Dakotas
state border vicinity as they consolidate toward 00-02Z.

..Kerr.. 06/27/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-UUJrUOQXevYiX3qrYejsw2MlWk11NDtmhAuSRJmgdpqqtrf2mPt8Y_oS51Q9JGgBvIUyZ2aY= DbUmrkcBeGBhm7da44$ for graphic product...

ATTN...WFO...BIS...UNR...BYZ...GGW...

LAT...LON 48770447 47440326 45400399 45510628 47470652 48120623
48770447=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


=3D =3D =3D
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* Origin: Capitol City Weather Station (1:2320/127)