ACUS11 KWNS 181951

SWOMCD

SPC MCD 181951 

MTZ000-WYZ000-IDZ000-182115-



Mesoscale Discussion 2026

NWS Storm Prediction Center Norman OK

0251 PM CDT Tue Aug 18 2026



Areas affected...southern Montana and far northern Wyoming.



Concerning...Severe potential...Watch possible 



Valid 181951Z - 182115Z



Probability of Watch Issuance...60 percent



SUMMARY...Isolated strong to severe storms are possible this

afternoon/evening across southern Montana and far northern Wyoming.



DISCUSSION...Storm coverage has increased across central and

southern Montana over the last hour ahead of a mid-level shortwave

trough. Relatively weak instability is in place amid mostly 40sF

dewpoints. However, strong heating (mid to upper 80s) has yielded

steep lapse rates across the region. Moderate mid-upper level flow

(40-55 kts) will support storm organization including the potential

for supercells. The weak instability should limit the hail threat

somewhat, but the steep lapse rates and dry sub-cloud layer should

support some severe wind threat, including the potential for a few

75+ mph wind gusts. 



Expect storms to remain mostly cellular which may limit a more

widespread severe wind threat. However, the stronger cores which

develop may be efficient wind producers. The downstream threat

across northern Wyoming remains uncertain due to extensive cloud

cover and limited heating.



..Bentley/Guyer.. 08/18/2026



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



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



LAT...LON   47280983 47230752 47090704 46760586 46080555 45370552

            44790570 44520692 44401010 44791160 46081135 47280983 



MOST PROBABLE PEAK WIND GUST...65-80 MPH

MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN