textproduct: Cheyenne

KEY MESSAGES

- Record breaking heat continues Sunday across the area.

- Another round of widely scattered afternoon and evening showers and thunderstorms is anticipated Sunday, which will have the potential to produce gusty winds and lightning.

- A plume of monsoon moisture will arrive on Monday, moderating temperatures and improving rainfall chances through Wednesday.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 323 PM MDT Sun Jul 26 2026

Storms are slower to initiate today as overall forcing is weaker than the previous day. There is ample mid-level moisture from the influence of the monsoon so satellite shows cumulus fields beginning to develop over the high terrain. Hi-Res guidance shows lower coverage of showers and storms today, with storms mainly hanging around the high terrain and Interstate 25 corridor. A few isolated storms could make it into the Nebraska panhandle but that would likely be later in the evening. Storms today will be of the mild variety, with gusty winds and brief heavy rain the primary concerns.

A strong push of monsoon moisture into the area on Monday will lead to widespread showers and storms through much of the day. This push of moisture will result in more cloud cover, meaning cooler temperatures. Highs will still be on the hot side, but will be roughly 5 degrees cooler compared to Sunday's temperatures. Moisture will arrive early, boosting PWATs up into the 90th percentile. As a result, showers and storms will likely begin to initiate during the morning, becoming more widespread heading into the afternoon hours. Model soundings aren't all that impressive, showing a mostly saturated column with a drier surface. As a result, soundings show a weakly inverted-V profile. With DCAPE values around 1000 J/kg, an isolated severe gust will be possible in storms. The main concern will be heavy rain with a marginal risk of flooding with slow moving storms and PWATs in the 90th percentile. Showers and storms will become less numerous during the evening hours, but will likely continue across portions of the CWA at least through midnight.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 323 PM MDT Sun Jul 26 2026

Higher probabilities of afternoon showers and thunderstorms will characterize the first portion of the long-term forecast period as an enhanced push of monsoonal moisture moves through southeast Wyoming and western Nebraska. Both ECMWF ensemble and GEFS ensemble guidance show PWAT normalized anomalies peaking near the 2 standard- deviations threshold through Tuesday and Wednesday afternoon. PWAT values between 1 inch and 1.25 inches are seen in forecast soundings during the afternoon hours on both days. Additionally, a bit of enhanced westerly flow aloft in the 500-200mb layer will round the apex of the monsoonal ridge over the southwestern CONUS on both days. This enhanced flow aloft, while certainly not extreme, will be just enough to add a bit higher bulk shear values to the convective setup on both days. It is not surprising that SPC is showing a marginal risk for some stronger storms on Tuesday, and likely this trend will continue on Wednesday. Convection will likely develop over the higher terrain of southeast Wyoming and drift east- southeastward by 18-20z. As outflow boundaries pool, expect a chance of isolated gusty winds perhaps occasionally to severe limits of 50 knots in the eastern high plains of Wyoming and western Nebraska. While temperatures will run slightly cooler the enhanced monsoonal moisture, deeply mixed afternoon forecast soundings continue to support a gusty wind threat on both days. Thunderstorms should have enough forward momentum to limit the risk of flash flooding. However, any location that does see repeated rounds of showers and thunderstorms could experience brief flash flooding concerns.

By Thursday, the monsoon high pressure over the southwest becomes a bit more suppressed and the plume of higher moisture values drifts eastward away from the Rocky Mountain region. As a result, expect lower chances of afternoon showers and storms from Thursday through next weekend. High temperatures will rebound somewhat as we dry out, but some uncertainty in the temperature and precipitation forecast emerges by the weekend. A frontal boundary from the northern high plains attempts to drop southward into the eastern plains of Wyoming and western Nebraska perhaps as early as Friday afternoon. Ensemble guidance varies greatly with regard to any impacts...ranging from only slightly cooler temperatures to a frontogenetically forced band of showers and cloud cover over the high plains on Friday evening, or perhaps on Saturday. With such low confidence from Day 5 onward in the forecast, we will message a more conservative outcome for now with slightly less hot weather and isolated shower chances. Regardless, significant precipitation seems unlikely through the end of the long term with generally above-average temperatures continuing for the foreseeable future despite a few frontal boundaries nearby.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 525 PM MDT Sun Jul 26 2026

Even though showers and thunderstorms may impact KCYS, KLAR, and KBFF over the next several hours, VFR conditions will prevail across all terminals through this TAF period. This activity should be all done by 06Z this evening, thereafter conditions become benign once again across all the sites with variable winds generally less than 6 knots. Another surge of moisture will begin to push into the area by 18Z Monday, increasing the chances of showers and thunderstorms across all the terminals. Right now, for this forecast period, the best chances of thunderstorms look to impact KCYS, KLAR, and KBFF. With chances spreading north and east just outside this forecast period.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Heat Advisory until 9 PM MDT this evening for WYZ101-102-107- 108-118-119. NE...Extreme Heat Warning until 9 PM MDT this evening for NEZ002- 095. Heat Advisory until 9 PM MDT this evening for NEZ003-019>021- 054-055-096.