617
ACUS11 KWNS 170746
SWOMCD
SPC MCD 170746
NEZ000-COZ000-WYZ000-170945-

Mesoscale Discussion 1326
NWS Storm Prediction Center Norman OK
0246 AM CDT Tue Jun 17 2025

Areas affected...parts of southeastern Wyoming into southwestern
Nebraska and adjacent northeastern Colorado

Concerning...Severe potential...Watch unlikely

Valid 170746Z - 170945Z

Probability of Watch Issuance...20 percent

SUMMARY...Stronger recent thunderstorm development near the Cheyenne
Ridge vicinity, probably accompanied by large hail, is expected to
weaken within the next hour or two, but trends will continue to be
monitored.

DISCUSSION...Strengthening, moist northeasterly to easterly
low-level flow into the Cheyenne Ridge has contributed to recent
strengthening of deep-layer shear and destabilization, in the
presence of large-scale ascent downstream of mid-level troughing
digging across the Great Basin into Rockies.  This has been
sufficient to overcome inhibition associated with warm elevated
mixed-layer air, to support scattered thunderstorms, including
supercells, above a relatively cool, stable boundary-layer.   Based
on radar, and reports, some of this has probably been accompanied by
large hail.  However, this convection may already be in the process
of diminishing, and this appears likely to continue, as the Rapid
Refresh suggests considerable weakening of the low-level upslope
regime during the next hour or two, in response to the progression
of the synoptic and sub-synoptic features.

..Kerr/Gleason.. 06/17/2025

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LBF...BOU...CYS...

LAT...LON   41700396 41740335 41250231 41060300 40870431 41150469
            41700396

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN