663
ACUS11 KWNS 152257
SWOMCD
SPC MCD 152256
NEZ000-COZ000-SDZ000-WYZ000-160100-

Mesoscale Discussion 2148
NWS Storm Prediction Center Norman OK
0556 PM CDT Wed Oct 15 2025

Areas affected...Northeast CO...southeast WY...western NE
Panhandle...and far southwest SD

Concerning...Severe potential...Watch unlikely

Valid 152256Z - 160100Z

Probability of Watch Issuance...20 percent

SUMMARY...The area is being monitored for an increase in
severe-storm potential into tonight. The primary concern will be
large hail, though locally severe gusts will also be possible with
southward extent. The need for a watch is uncertain.

DISCUSSION...The latest surface observations and visible satellite
imagery indicate an east/west-oriented quasi-stationary surface
boundary draped across the southwestern NE Panhandle into
southeastern WY, with widespread/persistent boundary-layer stratus
socked in to the north of the boundary. To the south, a mesoscale
surface cyclone is evident in the Denver vicinity, with a
northeastward-extending convergence zone across northeastern CO.

Convection has been attempting to form along the convergence zone,
though weak large-scale forcing for ascent has limited convective
initiation thus far. If a couple storms can evolve along the
convergence zone, upper 70s to lower 80s temperatures and
middle/upper 50s dewpoints will support surface-based inflow (around
1000 J/kg MLCAPE). This buoyancy and around 50 kt of effective shear
will conditionally support a surface-based supercell or two, with a
risk of large hail, locally severe wind gusts, and a low risk of a
brief tornado (given around 200 m2/s2 effective SRH). However,
overall confidence in the development of sustained surface-based
storms in this corridor remains low, especially given gradually
increasing nocturnal inhibition.

Farther north/northwest, convection is gradually increasing along
the higher terrain from north-central CO into central WY -- as
midlevel heights continue falling ahead of a substantial midlevel
trough moving across the Great Basin. While these storms will be
moving atop a cool/stable boundary layer, around 60 kt of effective
shear and steepening midlevel lapse rates will support elevated
supercell structures with a risk of large hail into tonight.

It is unclear if the severe risk will warrant a watch issuance,
though convective and environmental trends are being monitored.

..Weinman/Guyer.. 10/15/2025

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

ATTN...WFO...UNR...BOU...CYS...

LAT...LON   39670395 39870441 40580467 41090529 41580553 42030553
            42630537 43060504 43320450 43350388 43190325 42740298
            41720266 40920266 40450292 39680348 39670395

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN