973
ACUS11 KWNS 171856
SWOMCD
SPC MCD 171855
COZ000-NEZ000-WYZ000-172100-

Mesoscale Discussion 1333
NWS Storm Prediction Center Norman OK
0155 PM CDT Tue Jun 17 2025

Areas affected...Southeast Wyoming into the Front Range

Concerning...Severe Thunderstorm Watch 428...

Valid 171855Z - 172100Z

The severe weather threat for Severe Thunderstorm Watch 428
continues.

SUMMARY...Large to very-large hail remains possible with supercells.
Severe wind gusts are also possible, particularly with any upscale
growth that can move off the terrain. A tornado or two may still
occur with the most organized supercells.

DISCUSSION...The back edge of mid-level ascent with a shortwave
trough is now roughly along the Colorado western slope. Continued
moist upslope flow and lift from the trough will promote persistent
convective initiation along the higher terrain through the
afternoon. Steep mid-level lapse rates and moderate effective shear
(stronger with southward extent) should keep storm mode
supercellular. With slightly weaker shear and greater storm coverage
west of Cheyenne and Fort Collins, these areas would be preferred
for eventual upscale growth. Low-level stratus has eroded east of
these storms as well which will only further support moving off the
terrain over the next few hours. Severe winds and large hail would
be possible. Farther south, near Pueblo, the low-level stratus has
remained. Storms will likely remain near the terrain as a result.

Aside from hail and severe winds, a tornado or two will also be
possible. Low-level hodographs are not overly large per regional VAD
data, but low-level easterly winds, supercell modes, and numerous
storm-scale boundaries to interact with will allow for some risk.
One tornado has already been observed northwest of Cheyenne.

..Wendt.. 06/17/2025

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

ATTN...WFO...GLD...PUB...BOU...CYS...

LAT...LON   40840587 41920589 42290491 42180392 40130335 39350296
            38900286 38530299 38210417 38260531 38670575 40840587

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN