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 256 PM MDT Mon Aug 31 2026

A relatively quiet day across Southeastern Wyoming and the Nebraska Panhandle is expected ahead of an open wave that is currently lifting north and east across the Great Basin. Current mid-level water vapor imagery shows the next influx of monsoonal moisture associated with this shortwave trough, which has initiated some impressive convection over Southern Utah, resulting in localized flash flooding and even some large hail and damaging winds.

Ahead of the main wave, expect increasing clouds throughout the day with mostly dry conditions. High temperatures should peak in the low to mid 80s east of the I-25 corridor, with mainly mid 70s out west where cloud cover onset is expected earlier in the afternoon. This evening into the overnight hours is when the strongest (albeit 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. PWAT values overnight remain above the 95th percentile, however the main surge of monsoonal moisture is temporally offset from the strongest forcing. High resolution ensemble guidance has really backed off on QPF, with median values < 0.05 for all of our area.

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 tomorrow are expected to be slightly cooler than today, which will ultimately depend on how quickly showers and clouds depart our area. 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 /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 506 PM MDT Mon Aug 31 2026

Numerous showers and possibly a few thunderstorms are possible this afternoon into the overnight hours as a disturbance pushes through the area. This activity may drop flight categories close to MVFR CIGs and VIS for a short period of time, this is shown in PROB30 groups. 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.

CYS WATCHES/WARNINGS/ADVISORIES

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