ACUS11 KWNS 231958
SWOMCD
SPC MCD 231957=20
COZ000-NEZ000-WYZ000-232200-

Mesoscale Discussion 1278
NWS Storm Prediction Center Norman OK
0257 PM CDT Tue Jun 23 2026

Areas affected...northern Colorado into southern Wyoming

Concerning...Severe potential...Watch possible=20

Valid 231957Z - 232200Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorm development appears likely in the coming
hours from northern Colorado into southern Wyoming. Initially
high-based thunderstorms will intensify as they spread east into the
lower elevation. Watch issuance will likely be needed as this
occurs.

DISCUSSION...Gradual deepening and glaciation of cumulus is noted in
recent GOES day cloud phase imagery within the higher terrain of
northern CO and southern WY. This activity is largely being driven
by a combination of orographic ascent near the base of a layer of
steep mid-level lapse rates (observed between 7.5 to 8.0 C/km by
upstream 18 UTC RAOBs). Further deepening and the onset of lightning
production is expected within the next couple of hours as daytime
heating continues. The zonal flow regime aloft will advect cells
eastward into the adjacent High Plains where regionally rich
low-level moisture (dewpoints in the mid/upper 50s) is in place and
is supporting a plume of 1000-2000 J/kg MLCAPE. Convection emanating
off the higher terrain should be able to intensify within this
thermodynamic environment and mature into primarily discrete
supercells given around 45-50 knots of effective bulk shear.
Residual capping and fairly weak forcing for ascent away from the
terrain casts uncertainty on overall storm coverage, but storms that
can become sustained over the High Plains will likely pose a threat
for very large hail as well as severe wind gusts.

..Moore/Guyer.. 06/23/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!7Wh86R5h8yMqr89CV90GHCVRxxuGKKXkO_yRzwjAArRsLxrL_ZXchk8Te1gna0shLDrMvS1ME= Vr1D8ggwDQbK3ub-Ac$ for graphic product...

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

LAT...LON 38760482 40130559 40930615 41950705 42290701 42570649
42500565 42030466 41490417 40860368 39920320 39210304
38750306 38400331 38060395 37990434 38040475 38760482=20

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN


=3D =3D =3D
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