textproduct: Cheyenne

KEY MESSAGES

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

- 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 1242 PM MDT Tue Jun 2 2026

Looking like another active day across the forecast area with continued chances for severe thunderstorms this afternoon and through the evening hours. Current mesoscale analysis from late this morning shows the capping inversion has been virtually eroded across most of the Nebraska panhandle and areas west of the Laramie Range. The Interstate 25 corridor as well as Converse and Niobrara Counties remain capped, but are expected to erode away any surface based CIN within the next few hours. Healthy southerly flow, stronger than what models originally suggested, have helped mix the atmosphere, with daytime heating now helping prime the environment for severe storms. Model soundings as well as mesoscale analysis show healthy amounts of instability this afternoon, with MUCAPE values ranging from about 1500 to 2000 J/kg for areas east of the Laramie Range. Effective shear values are decent, and will be sufficient enough to get supercells as well as large hail. Hi-Res guidance shows initially discrete cells will transition to more of a disorganized line by this evening. This line could produce damaging wind gusts as storms become more outflow dominate. Cannot rule out tornadoes in today's set up with rather high MLCAPE values for our area, but higher LCLs may work to counteract this. Radar trends already show shower and storm development over the high terrain out west. Albany County also shows a ripe environment for severe weather so cannot rule out severe storms in and around Laramie this afternoon. Storms are also expected to form off a frontal boundary that is progged to move across eastern Wyoming later today. Greatest chance of severe storms in Wyoming will be between 2 PM and 6 PM this afternoon, with severe storms possible in Nebraska between 5 PM and 10 PM this evening.

Although severe weather chances are still possible on Wednesday, it will be a bit of a break from storms compared to the last few days. Weaker instability will create an environment conducive to marginally severe storms. The further eastward extent of the dryline modeled by the HRRR will also create a smaller areal extent for storms to develop. Hi-Res guidance shows the southern Nebraska panhandle as the most likely area for severe storms as this is where the highest instability is. Both severe hail and wind will be possible as both discrete cells as well as storm clusters are forecast for Wednesday. Mid to late afternoon is the most likely timing for storms with storms not expected to stray to late into the evening hours.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 1242 PM MDT Tue Jun 2 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. Recent model guidance has begun to pick up on lee cyclogenesis near the area in advance of the approaching upper level feature, but differ in its exact location. Exactly where this sets up will help determine where the most favorable area for strong to severe thunderstorms will develop. Currently, this appears most likely along the Lusk to Chadron corridor in east central Wyoming and into the northern Nebraska panhandle. This could also extend into the Chadron to Sidney corridor. Both of these areas have the highest confidence in dewpoints remaining high, whereas model guidance has been trending towards a drier surface airmass along and west of the I-25 corridor. Forcing will be provided by the approaching upper level low with current convective parameters appearing supporting of at least isolated strong to severe thunderstorms Thursday afternoon and evening.

Storm chances will drop back somewhat for Friday as drier air pushes eastward to encompass most of the forecast area. 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.

While precipitation on Friday looks very isolated, moisture will begin to slowly tick upwards again Saturday onward. Moisture will improve aloft first, increasing on Saturday. This could lead to a few isolated high-based showers and possibly a dry microburst hazard, but this is fairly low confidence several days out. Low- level moisture looks to recover Sunday into early next week, which will then allow for higher chances for appreciable precipitation, but also strong to severe thunderstorms. An early look from the ECMWF ensemble suggests fairly potent instability and thus more prevalent thunderstorm chances on Monday and Tuesday.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 543 PM MDT Tue Jun 2 2026

While thunderstorms have largely weakened, confidence is low regarding how this will play out later this evening. Storms still have the potential to flare up again, and could impact BFF, CDR, and AIA through about 04z. Confidence is highest in impacts near CDR, which has a TEMPO group, while the others are handled with PROB30. There is potential for strong, gusty winds, IFR conditions in heavy rainfall, and isolated large hail.

The low-level jet will keep strong southerly winds in place overnight, but this should weaken Wednesday morning as a weak cold front slips into the area. There is a slight chance for MVFR CIGs over the High Plains again tonight, but the probability is only around 20 to 30% at this time. Expect wind direction to shift around at all terminals except SNY during the day Wednesday. Wednesday's thunderstorm activity will be more isolated and limited, but additional chances for thunderstorms will be present near CYS, SNY, and possibly LAR, BFF, and AIA.

CYS WATCHES/WARNINGS/ADVISORIES

WY...None. NE...None.