textproduct: Cheyenne

KEY MESSAGES

- Strong ridging aloft will produce a dry and hot period for today through Tuesday, with the primary challenges being the above normal heat and fire weather conditions.

- Isolated high-based thunderstorms possible on Wednesday through the end of the week, along with a slow cooling trend. Temperatures will remain above normal though.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 123 PM MDT Sat Jul 11 2026

An upper-level ridge will become dominant over the region today, expect all levels including the surface, to dry out. This will bring some good and some bad. The good, expect a beautiful sunny afternoon, as evident on latest satellite imagery, with ample heating as highs soar into the 90s to near 100 for a few locations across our northern forecast counties. The bad, this heat coupled with min RH values tanking to around 15% across southeast Wyoming and to around 20% for the Nebraska Panhandle, makes the environment prime for elevated fire weather conditions/concerns. Therefore, we have a Fire Weather Watch in place through Sunday morning. Hi-res guidance, such as the NAM NEST, tries to show some widely scattered shower development this afternoon. However, due to the current environment we are in, this may be a little aggressive and nothing in fact may transpire. Rinse and repeat for Sunday, with the upper- level ridge continuing to dominate, dry conditions will continue and the Fire Weather Watch that is out will be upgraded to a Red Flag Warning from noon Sunday into Monday. This is in part due to our surface gradient tightening, resulting in winds becoming a tad gusty to around 25 mph. The 'warm' days will continue as lows only dip into the 60s and as such, therefore the Heat Advisory we are under will extend into the long term period as highs continue to soar into and through the 90s, with many locations possibly hitting the century mark.

LONG TERM /MONDAY THROUGH SATURDAY/

Issued at 123 PM MDT Sat Jul 11 2026

The weather over the medium to long range will be dominated by the quasi-stationary upper level high, forecast to remain over the south-central to central United States, including the Rocky Mountain region. To put it in perspective, models show the position of the upper level high (center) drifting westward by a few hundred miles from Monday to next Saturday. Therefore, not expecting conditions to change too much through next week.

For early in the week, broad center of the 600dm upper level high will be generally located in the central Rocky Mountain region extending northeast into the Great Lakes region. GFS and ECMWF standardized 500mb anomalies show between 1-3 SD's above average...which is pretty impressive since we're currently entering the hottest week of the year...climatologically speaking. Forecast high temperatures will be 90s for most of southeast Wyoming, including the high valleys west of the Laramie Range. For western Nebraska, 95 to 105 expected each day. There may be some silvering lining for the south facing ridges. Due to south to southeasterly winds, some localized upslope may prevent temperatures from climbing even higher. Kept temperatures a few degrees cooler (compared to the surrounding areas) in these locations, which include Cheyenne, Kimball, Sidney, Alliance, and Lusk. However, any westerly wind shift or light and variable winds will result in a rapid warm-up.

As we head into later in the week, center of the upper level high will drift overhead, and even retrograde westward a bit. Although winds will remain out of the southeast, or shift into the east during this time, wind speeds will decrease or become light and variable. This may actually lead to the hottest temperatures over the south facing ridges. Otherwise, temperatures will be a few degrees cooler across most of the area...although it will be hardly noticeable. Ensembles and NBM 75th to 90th percentile show high temperatures only a few degrees higher than the current forecast, so kept high temperatures close to the 50th percentile of the NBM. Low confidence on any precipitation during this time. Subtropical monsoon moisture is expected to creep north out of Mexico and the southwestern US. However, the position of the upper level high overhead may result in the monsoon moisture plume over Idaho, Utah, and western Wyoming. Therefore, most of the mention of POP and thunderstorms will be limited to the mountains and adjacent valleys for now through next Saturday.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 537 PM MDT Sat Jul 11 2026

VFR conditions are expected through the TAF period as high pressure sits over the area. Mostly clear skies are forecast through the night with relatively light winds. Winds will increase during the day tomorrow, with normal diurnal wind gusts of 20 to 30 kts.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Fire Weather Watch through Sunday morning for WYZ417-418-423- 430>433. Heat Advisory until midnight MDT Tuesday night for WYZ101-102- 107-108-118-119. Red Flag Warning from noon Sunday to 8 PM MDT Monday for WYZ417>420-423-427-430>433. NE...Fire Weather Watch through Sunday morning for NEZ434. Heat Advisory until midnight MDT Tuesday night for NEZ002-003- 019>021-054-055-095-096. Red Flag Warning from noon Sunday to 8 PM MDT Monday for NEZ434.