textproduct: Cheyenne

KEY MESSAGES

- Hot and dry conditions will persist through the end of the work week.

- Precipitation chances return for the weekend, with the possibility of widespread rain on Saturday.

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

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 239 PM MDT Thu Aug 20 2026

The rest of the afternoon is expected to be quiet as upper-level ridging strengthens over the Four Corners region. Cannot rule out a few stray showers moving into the western zones later this evening from remnant storms that developed in Utah this afternoon. Best timing for these showers will be between 8 PM and midnight tonight. Impacts will be minimal, with occasional brief strong wind gusts possible in and around showers. Most of the shower activity will be done my midnight, leaving calm conditions for the rest of the overnight.

Another mostly benign day is in store for Friday as the ridge continues to strengthen and gradually shifts eastward towards the Rockies. As a result, high temperatures will be about 3 to 5 degrees warmer compared to today's temperatures. The ridge will also do a good job keeping precipitation chances minimal, however, there are a few Hi-Res models, namely the HRRR, that show isolated showers and thunderstorms across southeast Wyoming. There is a decent amount of instability across the area Friday afternoon with some lift present from a weak upper-level disturbance moving through the ridge, so cannot rule out some storms. The main concern with storms, if they do develop, will be sudden, gusty winds as model soundings show ample amounts of DCAPE from the dry low-levels. Storm activity will ease after sunset, leading to a quiet overnight.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 239 PM MDT Thu Aug 20 2026

Saturday...Despite a prominent ridge axis stretching from eastern Montana southward through eastern Wyoming, there will be adequate amounts of pseudo monsoonal low and mid level moisture to produce scattered to numerous showers and scattered thunderstorms in the afternoon over and near our Northern Laramie, Snowy and Sierra Madre Ranges in the afternoon, with said convection spreading across the rest of our County Warning Area in the evening. The convection will be rather high based though with some decent efficient rain producers over the mountainous terrain. Somewhat cooler than Friday with additional cloud cover and precipitation coverage.

Sunday...The ridge aloft is flattened somewhat by shortwaves traversing in the flow, and with monsoonal moisture transported further east of our forecast area, coverage of showers and thunderstorms will be minimized to isolated to widely scattered high based activity.

Monday...Coverage of afternoon and evening showers and thunderstorms increases somewhat by an increase in pseudo monsoonal moisture and lowering 700 mb temperatures providing less convective inhibition, CIN, compared to Sunday. As is this type of pattern, afternoon convection will be over and near the mountains due to differential heating and orographic effects, with the activity spreading across the rest of the forecast area before dissipation by late evening. Warmer temperatures compared to the previous day due to less cloud cover and convective coverage.

Tuesday...Similar pattern synoptically to Monday with minor perturbations in the flow aloft aiding in lift of pseudo monsoonal moisture to produce widely scattered to scattered afternoon convection over and near our Snowy, Sierra Madre and northern Laramie Ranges, with the activity spreading eastward across the rest of the forecast area in the evening. Some lowering of mid level temperatures suggests daytime maximum temperatures will be a little cooler.

Wednesday...The primary change compared to Tuesday, will be a reinforcement of the ridge aloft axis over Wyoming, inducing a return to upslope mechanical lift aiding the areal increase of showers and thunderstorms, especially east of the mountains and along the I-25 corridor and eastward. Slight warming trend with 700 mb temperatures near 13 Celsius yielding high temperatures in the 80s.

Thursday...Monsoonal moisture becomes a bit more scant with decent westerly flow aloft and with warm temperatures aloft producing more convective inhibition, CIN, to limit development. A slight warming trend continues based on mid level, 700 mb temperature trends.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1209 PM MDT Thu Aug 20 2026

A dominant ridge aloft will persist through the period from the Four Corners to western Wyoming and limiting any significant shower and thunderstorm development due to warm temperatures aloft and minimal moisture in the low and mid levels. However, a weak disturbance moving under the ridge axis will produce isolated to widely scattered showers and thunderstorms affecting Carbon and Albany Counties of southeast Wyoming from late this afternoon through this evening.

Wyoming TAFSConfidence is high in VFR through the period. Recent trends of the HRRR suggest isolated to widely scattered showers and thunderstorms that may affect the KRWL and KLAR sites from late afternoon through early evening, though sparsity of said convection will be too minimal to include in the TAFs. As always, the strongest showers and thunderstorms will be capable of producing gusty and erratic winds and gusts and localized turbulence. Clouds clearing this evening.

Nebraska TAFSVFR expected with high confidence. Expect to see scattered high based cumulus through early evening, before dissipation. Winds will be relatively light and variable.

CYS WATCHES/WARNINGS/ADVISORIES

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