textproduct: Cheyenne

KEY MESSAGES

- A stormy weather pattern will setup Tuesday and Wednesday, continuing into the weekend with daily chances for afternoon/evening showers and thunderstorms.

- Strong to severe thunderstorms could be possible over the weekend into the beginning of next week.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 300 PM MDT Tue May 26 2026

An upper-level low settling into northern California/western Nevada today will lead to a stormy pattern in the short term. The placement of this low will put the CWA in southerly flow, allowing for access to Gulf moisture. The increased moisture aloft will fuel storm activity, with stubborn vorticity maxes over the area triggering storm initiation. Radar has begun to light up this afternoon, mainly over the high terrain west of the Laramie Range. Shower and storm activity, for the most part, will remain along and west of the Laramie Range as this is where the mid-level moisture is. Conditions east of the Laramie Range remain on the dry side with gusty south winds. Precipitation coverage will increase as the afternoon progresses, with coverage peaking this evening. The threat of severe storms this afternoon and evening will be low, with model soundings showing lower CAPE values and weak shear. Showers and storms will dissipate sometime after midnight as instability becomes negligible.

Wednesday will almost be a carbon copy of Tuesday, albeit a few degrees cooler with slightly wider coverage of storms. While the same areas of Carbon and Albany Counties can expect to see another round of showers and storms, the plume of mid-level moisture will begin to shift eastward. The strongest part of the plume will push into the Interstate 80 corridor, sparking isolated convection between Cheyenne and Sidney per Hi-Res guidance. The threat of severe storms will once again remain low with little instability and virtually no shear. A few lingering showers and storms will be possible after sunset, however most of the activity will be done before this.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 300 PM MDT Tue May 26 2026

Thursday we remain under the influence of a Rex block alongside a rather deep shortwave trough and associated vort max lifting off to the north and east over Western Nebraska. This will provide an additional source for ascent combined with PWAT values around the 95th percentile thanks to SW flow aloft. LREF guidance has around 400 J/Kg MUCAPE along the I-25 corridor and Laramie Range into Thursday afternoon, so the combination of moisture, lift, and instability should allow for widely scattered showers and thunderstorms. 0-6 km shear is progged to range from 15-20 knots, so severe weather is not expected. Due to the scattered nature and coverage of these showers and storms, 50th percentile QPF on Thursday remains below 0.1" for Southeastern Wyoming and Western Nebraska. High temperatures look to be around seasonal values to near 70 west of the Laramie Range, and mid-upper 70s over our Nebraska counties.

On Friday, the pesky closed low that has remained to our south and west throughout the week begins to get picked up by an 85-90 knot subtropical jet lifting north and east over the Baja Peninsula, gradually placing us in a region of stronger DCVA and therefore forcing for ascent. Again, the forcing at this time looks to be relatively weak, so no widespread rainfall is expected. Ensemble members are in good agreement that surface dewpoints along the Cheyenne Ridge will range from the upper 40s to the lower 50s under SSE upslope flow resulting in MUCAPE around 800 J/Kg. However thunderstorm coverage will depend on the amount of low-level cloud cover, which would ultimately keep us capped for most of the day. Regardless, effective bulk shear is expected to remain well below 20 knots, so severe thunderstorms are not expected. High temperatures will be near or slightly above climatology despite the potential for some low clouds.

Moving into the weekend, Saturday looks to be the most active day of the period, as the cutoff low transitions into an open wave and lifts over Wyoming and Nebraska. This will not only provide a greater source for lift, but flow aloft will also increase and effective bulk shear values are around 25-30 knots mainly over the Nebraska Panhandle. Forecast soundings indicate strong cap (MLCINH ~100 J/Kg) beneath a stout elevated mixed layer, however if storms can initiate in this environment with ~800 J/Kg of MLCAPE, they would have the potential to become severe. This will need to be monitored as we get closer to the weekend regarding the specific hazards, so stay tuned for future updates.

Sunday, the main wave departs our region and we remain in southwesterly flow aloft. This should result in the continuation of the ongoing moisture fetch, with ensemble guidance showing PWAT values near the 85th percentile of SE Wyoming and W Nebraska, allowing for additional chances for afternoon and evening thunderstorms through the remainder of the long term period. The ridge to our east begins to amplify resulting in 500 mb height rises, so can expect a brief warming trend towards the end of the weekend and into the work week.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 530 PM MDT Tue May 26 2026

Ongoing showers are within the vicinity of KRWL and KLAR which are influencing short term winds. Another pulse of rain showers are possible in the next few hours over these terminals which may drop ceilings and reduce visibilities. MVFR conditions may occur with in the heaviest cores. These showers should dissipate around 06z. Tomorrow morning and into the early afternoon expect scattered to broken mid and high level cloud coverage at terminals with wind gusts to 20-30 kts. Another area of showers and thunderstorms are expected after 20z and may impact KLAR. Elsewhere VFR conditions should prevail.

CYS WATCHES/WARNINGS/ADVISORIES

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