textproduct: Cheyenne

KEY MESSAGES

- Scattered to numerous showers and thunderstorms expected this weekend, with the possibility of widespread rain on Saturday. A few strong to marginally severe thunderstorms possible Saturday afternoon. Flash flooding is also possible.

- Daily shower and thunderstorm chances continue Monday through the end of the week with slightly above average temperature expected until Thursday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 130 PM MDT Sat Aug 22 2026

Another active day is expected this afternoon and evening as a shortwave passes through the upper-level ridge, bringing with it a push of monsoon moisture. Much like yesterday, the early development already being seen is weak and pulsey due to a decent amount of MLCIN still present. As the afternoon progresses, CIN will erode and storms will take advantage of the ample amounts of SBCAPE that the RAP is predicting later this afternoon. The shortwave will provide the lift for storms to develop while decent shear will allow for a few organized cells to sustain themselves. For the most part, hodographs are fairly linear, so multicell clusters and perhaps a small line or two are the favored storm modes. This is supported by Hi-Res guidance showing a similar solution. Although strong winds will be the primary concern in storms, embedded large hail could also be possible. With the monsoon push, PWATs are in the 90th percentile with model soundings showing rather slow cloud layer winds. As a result, heavy rains are expected with flash flooding a possibility. Along with flash flooding, a few severe thunderstorms cannot be ruled out. Although storms are already beginning to fire, the strongest storms are most likely 4 PM and 9 PM this evening. After this timeframe, linger scattered showers are expected throughout southeast Wyoming and western Nebraska for the better part of the overnight. With the remnant moisture from storms and weak southerly flow overnight, patchy fog and low stratus could once again be possible for areas east of the Laramie Range, including the Nebraska panhandle.

Sunday does not look as active as Saturday, although precipitation chances are still forecast. The ridge will flatten slightly as a trough skirts the Canadian border. This will cause winds to turn more westerly, which will help dry the low-levels a bit compared to Saturday. The westerly winds also cut down on instability, with model soundings only showing about 1000 J/kg of CAPE. As a result, Hi-Res guidance shows less coverage of storms across the forecast area. Any storms that develop on Sunday are not likely to be severe. With the westerly winds, gusty conditions are expected out west. A decent MSLP gradient will set up with 40 kt winds aloft. This could lead to 40+ MPH wind gusts during the afternoon and evening hours. Winds as well as any showers will dissipate overnight.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 130 PM MDT Sat Aug 22 2026

Moving into the work week we'll start off on the hot side with a high pressure ridge firmly in control of the Western US. While temperatures will cool just a couple of degrees compared to Sunday, highs still sit warmer than average by around 5-8 degrees. A cold front will be approaching the region with another round of afternoon showers and thunderstorms on tap including locally stronger to weakly severe activity possible. By Tuesday though a backdoor cold front will offer very meager respite as highs drop by around 2-6 degrees, closer to near average but still above by up to a few degrees. Similarly, moisture will continue to remain just above average at around 120-140% of average, equating to PWAT values of 0.75-1.25 inches. While not impressive by any stretch of the imagination, this should continue to fuel daytime thunderstorms with a marginal risk of severe activity. Wednesday through the end of the week look to be largely similar with a steady warming trend, bringing us back to temperatures similar to Monday alongside continued daily afternoon thunderstorm risk under westerly to northwesterly flow. Drier air will slowly infiltrate through the week though, and this will begin to steadily increase our fire weather risk with elevated conditions at least by Friday. Anyone expecting an early end to summer will be sorely disappointed in the last full week of August.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1136 AM MDT Sat Aug 22 2026

A mix of flight categories expected over the next 24 hours. Some low stratus are beginning to clear away from BFF, but may linger for another hour or two. Thereafter, look for mid level clouds to move in through the day, with thunderstorms possible this evening across all sites. Any storms could lower CIGs to MVFR status, with MVFR to possibly brief IFR VIS. Thereafter, clouds will lift and clear through the night into tomorrow morning. Winds breezy at 15-25 knots, higher with any nearby storms causing gusty and erratic conditions, with similar winds overnight into tomorrow morning.

CYS WATCHES/WARNINGS/ADVISORIES

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