ACUS11 KWNS 201850

SWOMCD

SPC MCD 201850 

WYZ000-202045-



Mesoscale Discussion 1211

NWS Storm Prediction Center Norman OK

0150 PM CDT Sat Jun 20 2026



Areas affected...Wyoming



Concerning...Severe potential...Watch possible 



Valid 201850Z - 202045Z



Probability of Watch Issuance...40 percent



SUMMARY...High-based thunderstorms capable of severe downburst winds

will spread across central and northeast Wyoming through the

afternoon. Trends are being monitored for the need for a watch

issuance, though thunderstorm coverage remains uncertain.



DISCUSSION...Over the past 1-2 hours, relatively shallow, but

high-based, convection has begun spreading across western WY with a

second region of storms more recently developing within the Wyoming

Basin/southern WY. Across both regions, clearing skies ahead of the

developing storms has allowed surface temperatures to warm into the

70s with dewpoints mixing into the mid to upper 30s. Based on recent

forecast guidance, these surface conditions suggest that the

boundary-layer has now fully mixed to around 3 to 3.5 km deep with

around 250-500 J/kg of MLCAPE. Although buoyancy is fairly meager,

the combination of a deeply mixed boundary layer and 30-35 knots of

effective shear should promote persistent convection capable of

producing strong to severe downburst winds. Latest CAM guidance

continues to depict this threat well and suggests swaths of 50-75

mph winds may emerge across central to northeast WY through the

early evening hours. 



The primary uncertainty in the short-term forecast is the lingering

cloud cover further downstream across central/northeast WY, which is

muting diurnal heating (temperatures remain in the 60s) and limiting

boundary-layer depth. Although this cloud cover is rapidly

progressing northeast, it is unclear if the window of mostly clear

skies will be sufficient to produce a deeply-mixed boundary layer

conducive for severe winds. Consequently, confidence in the severe

wind threat is greatest in the near-term, but some severe wind

threat may materialize further downstream through the evening if

sufficient heating can occur. Convective trends are being monitored,

and watch issuance may be needed.



..Moore/Hart.. 06/20/2026



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



ATTN...WFO...UNR...CYS...BYZ...RIW...



LAT...LON   41590803 41560864 41810917 42790999 43380985 43820942

            44730731 44770647 44650585 44370528 44010471 43560421

            43280411 43290414 42950408 42050407 41540430 41260460

            41160491 41210540 41490579 41700619 41790658 41750715

            41590803 



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

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