textproduct: Cheyenne

KEY MESSAGES

- There is a slight risk (level 2 of 5) across the eastern high plains on today. Large hail, severe wind, and an isolated tornado will be possible once again.

- The potential for a few afternoon and evening strong to severe thunderstorms will continue through the remainder of the work week.

- Temperatures will slowly warm to well above seasonal averages by the weekend as thunderstorm chances become more isolated.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 315 AM MDT Tue Jun 2 2026

Unsettled weather continues as a upper-level trough continues to slowly spin over the Montana/Saskatchewan border and will slowly move along the Northern Plains/Canadian Border. At the surface, a frontal boundary will move across the Intermountain West and will interact with moist and unstable air (dew points in the 50's and lapse rates between 8.5-9.0), supporting multiple rounds of showers and thunderstorms. With large scale forcing and sufficient amount of moisture, chances for clustering along the boundary and high rain rates will be possible. SPC has extended their Slight Risk area further south to include the northern half of the Nebraska. Hi-Res models put the 0-3km SRH values between 200 and 350 m2/s2 presenting the slight chance for landspouts and Tornados as well the potential for decent sized hail. However, there will be a semi-strong cap over the Nebraska Panhandle that may limit severe thunderstorms from producing at all. Model soundings prog the convection temperature for today as being between 75 and 81 degrees by this afternoon. With the forecasted high temps to be in the 70's and 80's there's a chance the CIN alone may be high enough to prevent any thunderstorm that floats into the Panhandle loses momentum and never amounts to anything more than a garden variety storm. Going off convective temp alone Scottsbluff looks to be the best potential area for storms to go severe and take advantage of the possible 1200 joules of MLCAPE depicted by the RRFS. However the better environment looks to be the where the original slight risk was, further north into South Dakota near Rapid city.

Wednesday, A shortwave disturbance will develop along the northwest, bringing scattered showers and thunderstorms across the Intermountain West. Model soundings show a chance for our convective party to continue Wednesday as well. The soundings show the cap eroding by the afternoon/evening time frame with steep lapse rates. Dewpoints may be only in the 40's and 50's but that will be sufficient to produce a severe thunderstorm. However, The environment tomorrow wont be as primed and explosive as it is today. Models depict MLCAPE being between 100-300 joules with the MUCAPE maxing out around 800 joules. SRH(0-3km) is barely 100 m2/s2 and the models show every parameter rapidly decreasing after 00z pumping the brakes on our party once the sun starts to set signifying an overworked environment.

On the other side of things, Carbon county looks to continue to get missed with any sufficient moisture for today and tomorrow. The RH values for Carbon county look to be between 10 and 15 percent for the vast majority of the county. In March, fuels were reported to be in green up but this stretch of no moisture may eventually start to cure the grasses and other fuels slowly increasing their chance for combustibility. So while a Red Flag isn't going to be issued, keep an eye on any flames and burn responsibly.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 900 PM MDT Mon Jun 1 2026

Looking ahead to Thursday, another upper level shortwave trough right on the heels of the departing primary low will move across the northern Rockies. This will provide synoptic forcing for additional rounds of afternoon and evening thunderstorms in place of continuing low-level instability and modest wind shear over the High Plains. We are getting a little far out to discuss details of the potential convective threat, but parameters suggest at least isolated strong to severe thunderstorms.

Storm chances will drop back somewhat for Friday. A deep Pacific trough pushing into the northwest CONUS will amplify the downstream ridge over the Rockies and Plains, pushing temperatures upward into the weekend. Most areas will reach the 80s on Friday, with fairly widespread 90s possible Saturday as the ridge axis shifts overhead. 700-mb temperatures peaking around +12 to +16C will be around the climatological 90th percentile. Sunday's highs may drop slightly for our western zones, but should be fairly similar to Saturday over the High Plains, with widespread mid 80s to mid 90s. Current forecast remain comfortably below daily record highs, but it will certainly be a warm to hot few days. Ensembles have developed quite a bit of spread in the outlook for surface moisture during this period, which will feed back into the outlook for precipitation. The most likely scenario at this time is a drier lower atmosphere promoting more limited thunderstorm chances on Friday and Saturday, but moisture and storm chances may begin to creep back up on Sunday and into early next week.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 537 AM MDT Tue Jun 2 2026

Some fog has formed near KLAR and is currently dropping visibilities at KCYS. By 15z the fog should be all burned off and vis should be back up to p6sm. Clouds will slowly start to fill in some as we have some high level clouds pushing through this morning. Storms are expected to develop around 19z for KLAR and KCYS. Rain showers look to dance around KRWL but no rain is expected to impact the airport. After 00z the Showers may turn into thunderstorms as they cross into the Panhandle today. There is a strong capping inversion today that may limit the storm potential this afternoon and evening. If that happens then the thunderstorms may still form but they will likely be weak and definitely not severe. By 03z all convection looks to be done and the skies will probably clear out.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Dense Fog Advisory until 9 AM MDT this morning for WYZ116>118. NE...None.