textproduct: Cheyenne

KEY MESSAGES

- Showers and thunderstorms are expected through tonight. Strong wind gusts and heavy rainfall possible.

- Drying and warming trend expected going into mid to late week with growing potential for elevated fire weather conditions, mainly north of Interstate 80.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 1109 PM MDT Mon Aug 31 2026

Conditions are relatively quiet this evening across the region with a few showers mainly across Southeastern Wyoming. This is being driven by a weak open wave which is providing a source for DCVA across our region. Current mid-level water vapor imagery continues to show a plume of monsoonal moisture being advected north and east over Southeastern Wyoming, which will continue to push north and east towards the Nebraska Panhandle overnight into the early morning hours before the bulk of this weak system lifts to the northeast.

Overnight is when the strongest (albeit fairly weak) forcing for ascent is expected. Not anticipating too much in the way of thunderstorm activity as MLCAPE is progged to be <100 J/Kg as a result of poor low-level lapse rates and surface dewpoints in the low to mid 40s, but cannot rule out a rumble of thunder with any of the heavier showers. The main threat overnight will be localized flash flooding, mainly over portions of Carbon and Albany Counties where the greatest collocation of total column moisture and forcing will be, as PWAT values overnight remain above the 95th percentile. Further, forecast soundings suggest cloud-layer mean winds of 10-15 knots, so any slow-moving convective elements could pose a flooding threat. Further east, the bulk of the forcing from the shortwave trough isnt temporally collocated with the main moisture surge. This should limit any hydrological issues primarily east of the I-25 corridor.

Showers are expected to gradually decrease in coverage from southwest to northeast from late morning through early afternoon on Tuesday as the wave ejects off to the north and east of our area. High temperatures Tuesday are expected to be slightly cooler than Monday, which will ultimately depend on how quickly showers and clouds depart our area. We can expect westerly winds to remain breezy, with gusts peaking from 25-30 mph mainly east of the Laramie Range.

Tuesday night, shortwave mid-level ridging will establish itself over the Northern Great Plains with a continuing trend of decreasing cloud cover. Overnight temperatures will remain quite mild, especially north of the Pine Ridge where 10-25 knot southerly low-level flow will help to moderate temperatures thanks to downsloping.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 256 PM MDT Mon Aug 31 2026

Wednesday...Brisk southwest flow aloft prevails. Low and mid level moisture availability looks scant, thus POPS near zero and negligible. Based on the low and mid level gradients, it looks like it will be windy.

Thursday...Similar day to Wednesday with rather strong and dry southwest flow aloft and decent and deep unidirectional southwest flow for a windy and dry day.

Friday...The flow backs to south southwest and weakens somewhat, with minor influx of pseudo monsoonal mid level moisture, though confidence in shower and thunderstorms development is negligible thus will keep it dry.

Saturday...Looks like a pseudo moisture tap will emanate up from the Four Corners with an uptick in PWAT, Precipitable Water Content, noted, thus expect isolated to scattered afternoon showers and thunderstorms for our Snowy and Sierra Madre Ranges, with the activity spreading northeastward and remaining mostly west of I-25 in the evening.

Sunday...Once again, the rather moist southwest flow will tap pseudo monsoonal moisture and diurnal heating and orographic effects will help produce scattered showers and thunderstorms in the afternoon for locations over and near the Snowy and Sierra Madre, and northern Laramie Ranges, with the convection spreading across the remainder of southeast Wyoming and western Nebraska in the evening.

Monday...Ridging aloft over the Central Plains states bulges westward across our counties, though with adequate low and mid level moisture, we still anticipate scattered afternoon and evening showers and thunderstorms.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1109 PM MDT Mon Aug 31 2026

Numerous showers and possibly a few thunderstorms are possible this evening, lingering into the overnight hours for KAIA and KCDR as a disturbance pushes through the area. This activity may drop flight categories close MVFR CIGs and VIS for a short period of time. The main aviation hazard with this activity will be the gusty and erratic winds that accompany any storm or shower, with speeds up to 35 knots. After this leaves the area, there will be a lull in winds for several hours then they will ramp back up during the daytime hours back with gusts 20 to 30 knots for the southeast Wyoming terminals. The Nebraska sites will see winds generally less than 10 knots for the duration of this forecast period.

CYS WATCHES/WARNINGS/ADVISORIES

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