textproduct: Cheyenne

KEY MESSAGES

- Active with scattered to numerous showers and thunderstorms into the weekend. Strong to marginally severe thunderstorms may return to the area as a potent Pacific storm system moves into Wyoming Saturday and Saturday night.

- Active weather with cooler temperatures expected for much of the upcoming week.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 259 PM MDT Fri Sep 18 2026

An active evening and weekend is in store for us. The upper level low is further south than what the models originally had when comparing current satellite Water vapor to global model outputs. The position of the upper level low will really be important over the next 48 to 72 hours. There is a low amplitude ridge over the southern plains that if the central pressure shifts a little west will slow down this low. If that occurs, expect heavy rain showers and borderline severe to severe thunderstorms over the weekend. Judging by its current speed and anticipated trajectory this low is more likely to straddle the Colorado/Wyoming giving us decent widespread rainfall but a little bit less likely on the severe aspect. Hi-res guidance puts about 500 to 1000 joules east of I-25. There are some pockets of 2,000 joules which may be over done with the okay lapse rates between 6.5 to 7.0c and 700mb temperatures between 8 and 10C. Some cold air will be following this low dropping 700mb temperatures from 10C to 6C leafing to high temperatures slowly dropping through the weekend. By Sunday the high temperatures are in the 60's and the forecast area may be a little too cool for severe weather but heavy rainfall looks to be a daily afternoon and evening occurrence.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 259 PM MDT Fri Sep 18 2026

Forecast for next week looks to remain largely the same from day to day under weak pressure gradients aloft with a few chances for some scattered precipitation, but otherwise a cool start to the weak with a slow and steady warming trend through the remainder of. Upper level pattern will consist of weak ridging trying to build in on Monday, but this will be overtaken by a weak low lifting up from California and slowly progressing across the region through the end of the forecast period. At the surface, Monday will see our forecast region in a post-frontal environment, with a weak boundary then sitting across the WY/NE border area and then lifting east-northeast as a warm front into the later days of the week. Under this pattern Monday will be the coolest day of the forecast period as widespread highs generally sit in the 60's to right around 70 in the warmest spots. Increasing warmth then expected as warmer air from the southwest moves across the region, but don't expect a crazy warmup as we increase only 1-3 degrees each day, keeping the region mostly in the 70's through the week until Thursday when a few more 80's may finally begin popping up. A brief blip of moisture may produce increased chances of showers and storms on Tuesday as the California low lifts up, but without a stout forcing mechanism don't expect much outside of general showers and thunderstorms and coverage isolated to scattered at best. Otherwise, a few isolated showers or storms possible each day as well with nothing impactful expected.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1142 PM MDT Fri Sep 18 2026

Regional radars show a complex of showers and storms moving through the NE Panhandle. Terminals in this location have had periods of MVFR and IFR conditions. The current activity is expected to linger for the next few hours but decrease in intensity. Behind it calm winds and saturated near surface layer should be favorable for fog development, or best case lowered CIGs through about 17z. At the Southeast Wyoming terminals showers continue to move east. Brief periods of MVFR conditions are possible with these showers. Winds become variable and weak at most terminals overnight and into the morning. Another round of storms and showers develop after 18z and move northeast. Gusty winds, to 45 knots, reduced visibility, lightning, and IFR level CIGs are possible. Late in the forecast period additional fog is possible.

CYS WATCHES/WARNINGS/ADVISORIES

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