textproduct: Western and Central Wyoming

KEY MESSAGES

- Shower and thunderstorm chances (30%-70%) occur through 9PM, with the greatest coverage across the northwest Wyoming. Thunderstorms will be capable of gusty outflows up to 45 mph and lightning.

- Shower and thunderstorm chances exist each afternoon through at least Sunday, with more widespread showers and thunderstorms Friday through Sunday.

- High temperatures are forecast to be in the upper 70s to 80s each day. A few locations east of the Continental Divide could see highs in the 90s Wednesday through Friday.

UPDATE

Issued at 1144 AM MDT Tue Aug 25 2026

Patchy clouds are moving across northern Wyoming late this morning. Some cumulus are starting to build over the mountains as daytime heating increases. Isolated showers and thunderstorms are still expected across the area this afternoon and evening, with the majority of them initiating off the higher terrain. Gusty outflow winds to around 45 mph are possible with any shower or storm. Brief moderate to heavy rain is also possible with the stronger storms, especially over western Wyoming where precipitable water (PWAT) values are better. Most activity ends with the setting sun today, though a few showers could linger around the Yellowstone area through midnight.

DISCUSSION

Issued at 159 AM MDT Tue Aug 25 2026

Showers and a few embedded thunderstorms across southwest Wyoming are being supported by a shortwave disturbance early this Tuesday morning. This shortwave and the associated showers and thunderstorms will shift east across the Green River Basin and Sweetwater County and fizzle out by sunrise. This shortwave is rounding an upper level high that is centered over New Mexico and Texas.

Today, this upper high will build north into the Great Basin, with it's ridge axis extending into Idaho, placing Wyoming in west- northwest flow aloft. An embedded disturbance will traverse across the state and provide support for showers and thunderstorms this afternoon and evening. Shower and thunderstorm coverage is forecast to be less widespread compared to Monday and be largely orographically and diurnally driven along and east of the Continental Divide. Available moisture will be greatest across the aforementioned areas thanks to the west-northwest flow aloft and an associated boundary dropping into northern and central Wyoming. Thunderstorms are expected today with lifted indices ranging from -1C to -3C and BLCAPE values around 500 J/kg; however, height rises aloft will hinder severe thunderstorm potential. That being said, a few showers or thunderstorms will be capable of gusty outflows up to 45 mph. Showers and thunderstorms are forecast to develop between noon and 2PM across the higher terrain along the Continental Divide and shift east-southeast through the afternoon. Shower and thunderstorms largely come to an end by 9PM tonight, with a few light showers possible across northwest Wyoming until 11PM. With 700mb temperatures around 10C, anticipate high temperatures in the upper 70s and 80s.

The upper level ridge is forecast to begin a slow shift east across Wyoming early Wednesday and be east of Wyoming by Thursday evening. The ridge axis is currently forecast to be over western Wyoming on Wednesday as another weak disturbance propagates around it. Although there will be some support and available moisture aloft, height rises will keep shower and thunderstorm activity orographically and diurnally driven across southwest Wyoming and along and east of the Continental Divide. On Thursday, the ridge axis shifts east across Wyoming and places western Wyoming in west-southwest flow by peak heating. This west-southwest flow will funnel Pacific moisture into the area and provide support for diurnal shower and thunderstorm development across west and northwest Wyoming. Because the ridge is over Wyoming on both Wednesday and Thursday, temperatures are expected to warm into 80s west of the Divide and mid 80s to mid 90s east of the Divide both afternoons.

Ensemble guidance is in consensus that the Intermountain West will be positioned between the ridge in the central CONUS and an approaching Pacific Northwest trough on Friday. This places Wyoming in southwest flow with Pacific moisture funneling into the region. This looks to be the pattern Friday through at least Sunday morning as the Pacific Northwest trough shifts east. The specific details on timing, precipitation amounts, and coverage are unknown at this time, however, confidence in an active weather weekend is increasing.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 356 PM MDT Tue Aug 25 2026

VFR conditions are expected to prevail through the period. Any exception will be due to brief heavy rain associated with showers or thunderstorms in the area . However, this is not expected to be as robust as yesterday, and coverage is accordingly decreased. Outflow wind gusts will be the more widespread concern, with gusts of 30 to 40 knots possible. Most of this activity will wane after sunset, with any lingering showers coming to an end after around 06Z. Lighter wind and decreasing clouds are expected through Wednesday morning. Convection chances return Wednesday afternoon, though again not as widespread; the best chances will be at KBPI, KCOD, and KPNA where PROB30 groups have been added. Confidence is lower at remaining terminals for now.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

None.