ACUS11 KWNS 231920
SWOMCD
SPC MCD 231919
MTZ000-WYZ000-IDZ000-232115-

Mesoscale Discussion 2099
NWS Storm Prediction Center Norman OK
0219 PM CDT Sun Aug 23 2026

Areas affected...Central Montana and adjacent portions of Idaho and
northwest Wyoming

Concerning...Severe potential...Watch possible

Valid 231919Z - 232115Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorm development is expected in the coming hours
within the northern Rockies. This activity will likely intensify as
it spreads east across central Montana and portions of northwest
Wyoming. Watch issuance is probable over portions of the region
given the downstream convective environment.

DISCUSSION...Growing cumulus is evident in latest GOES imagery
within the higher terrain of northwest WY and eastern ID/western MT
due to a combination of daytime heating and increasing ascent (both
orographic and dynamic lift ahead of an approaching upper wave).
Regional VWPs are also depicting increasing mid-level flow
associated with the approach of the upper wave, resulting in gradual
elongation of hodographs across the region. Concurrently,
temperatures downstream across central MT are warming into the mid
to upper 80s, which appears sufficient to erode lingering inhibition
and support around 500-1000 J/kg MLCAPE based on modifications to
forecast soundings. Consequently, it appears likely that
thunderstorm development will occur in the coming hours as ascent
continues to spread east over the destabilizing air mass.

Recent guidance supports this notion and depicts initially discrete/semi-discrete cells across the region. This early activity
will likely pose a threat for large hail (most likely 1 to 1.75 inch
in diameter) given adequate hodograph elongation. With time,
clustering and upscale growth should support an increasing wind
threat across central MT through the late afternoon and evening
hours. Based on the downstream environment and recent high-res
guidance output, wind speeds up to 60-80 mph appear possible with
the more intense/organized clusters. Watch issuance is probable in
the next 1-2 hours as thunderstorms begin to develop and mature.

..Moore/Smith.. 08/23/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!9LGfX4Nr_U5iqnU5v6iZVX5fFd_Niatgzw9Jn0k4DPa46RVCueSIy_WIXRjMdy2-34hUDny7y1B7QhCzlyqoKc4wFC4$ for graphic product...

ATTN...WFO...BYZ...GGW...RIW...TFX...PIH...

LAT...LON 43580985 43721101 43891184 44241224 44671230 45951204
46121196 47331187 48601189 49021155 49060898 48330862
47280851 46360853 45420852 44250862 43730882 43580908
43580985

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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* Origin: capitolcityonline.net * KY, USA (1:2320/107)