textproduct: Cheyenne

KEY MESSAGES

- Hot, dry, and breezy conditions continue through Sunday before a much awaited cold front arrives for the start of the week.

- Monday looks to be the last 100+ day for the upcoming week or so, with reduced fire concerns also arriving with cooler weather.

- Monsoonal moisture will attempt to return as early as Monday, leading to increased precipitation chances through much of next week.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 220 PM MDT Fri Jul 17 2026

The short term should remain fairly similar to the last several days as high pressure ridging continues to sit over the region with warm temperatures today in the upper 80's to near triple digits, increasing a few degrees with nearly widespread 90's to 100's across the area on Saturday. Because of this increase in coverage of triple degree heat, a Heat Advisory was issued beginning Saturday for portions of Sioux and Dawes counties, with several more zones added in beginning on Sunday. We should also continue to see elevated fire weather conditions as surface relative humidity values sit in the 15-20% range while breezy, diurnally driven winds of around 20-25 mph will be present, but if any site is able to reach critical criteria for fire weather conditions it's not expected to persist for 3 or more hours. Finally upslope flow today may once again fuel an isolated shower or storm across our high elevation and mountainous locations in Carbon and Albany Counties, but with inverted V sounding profiles precipitation may struggle to reach the ground under weaker cells, and instead we could see the potential for a rogue dry lightning strike or gusty outflow winds. Monsoonal moisture attempts to finally swing into the region on Saturday, but guidance has dialed back or precipitation chances with Carbon and Albany County once again at an isolated to widely scattered probability of seeing some development. Better moisture should return just beyond the short term on Sunday and thereafter.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 220 PM MDT Fri Jul 17 2026

Sunday...GFS progs the ridge aloft over the northern Rockies to be flattened somewhat with zonal flow developing over Montana and northern Wyoming. A weak perturbation, or shortwave trough aloft, will move across our counties in the afternoon and evening, with monsoonal moisture advecting into our western counties west of I-25, where we anticipate scattered showers and thunderstorms to develop in the afternoon west of I-25, with the greatest areal coverage over the Snowy, Sierra Madre and northern Laramie Ranges. So, more beneficial rain will occur.

Monday...Monsoonal moisture at low and mid levels increases further, aiding in another increase in late day shower and thunderstorm coverage, and beneficial rains, with coverage increasing to scattered 30 to 60 percent POPS, probability of measurable precipitation, with the greatest coverage over and near our mountain zones.

Tuesday-Friday...A relatively significant pattern change will occur, with "beware" northwest flow aloft developing along with a decent increase in low and mid level moisture and upslope southeast mechanical lift at low levels, and occasional passing shortwave troughs aloft, helping to produce scattered to numerous showers, and scattered thunderstorms in the afternoons and evenings, with beneficial rainfall and possibly some locally heavy rains from some of the slower moving thunderstorms. The most likely locations for locally heavy rain and the greatest areal coverage may be along and east of Interstate 25. On Friday, the GFS progs the last of the passing shortwave troughs aloft to move into Nebraska by evening, with shortwave ridging aloft bulging across Wyoming, thus expect an attendant decrease in areal afternoon and evening shower and thunderstorm coverage.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 524 PM MDT Fri Jul 17 2026

Regional radars are clear this evening. Winds out of the south to southeast between 10 to 15 knots. A stationary front in the northern Nebraska Panhandle is expected to drift south and could lower ceilings at KCDR and KAIA overnight. Very low chance of fog at KCDR. Winds calm to become variable at most terminals during the late overnight and early morning hours.

Tomorrow afternoon diurnal heating will create scattered cloud coverage and increase winds out of the east to southeast at 10 to 15 knots. At KRWL enough shower and storm coverage is present in hi resolution models to introduce a prob30 group into the TAF. The stationary front could be a focal point for some isolated to scattered showers and storms which could impact KAIA. Chances are too low at this time to introduce a prob30.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Heat Advisory from noon Sunday to 6 PM MDT Monday for WYZ101- 102-108. NE...Heat Advisory from noon Saturday to 6 PM MDT Monday for NEZ002- 095. Heat Advisory from noon Sunday to 6 PM MDT Monday for NEZ003- 019>021-096.