textproduct: Western and Central Wyoming

KEY MESSAGES

- Elevated to near-cricital fire weather conditions occur Friday and through this weekend, with widespread gusty winds (20 to 40 mph) and low humidity (less than 15 percent).

- Hot Saturday, with highs in the 80s west of the Divide, and mid-to- upper 90s east of the Divide. Cooler air moves in for Sunday, dropping highs around 10 degrees and bringing slight (15 to 40 percent) rain chances, mainly for northern Wyoming.

UPDATE

Issued at 956 AM MDT Thu Jun 4 2026

No major changes to the forecast with this update. Current water vapor shows the shortwave moving through northern Wyoming at this time, with a decent number of clouds. This feature tracks eastwards through this evening. The main result of this is the chance for showers and thunderstorms, some of which could be strong to severe. The better threat for strong storms exists north and east of the area, but northern Johnson County could see a strong storm between 3pm and 7pm; the main hazards are winds up to 60 mph and small hail.

DISCUSSION

Issued at 243 AM MDT Thu Jun 4 2026

KRIW radar noting very light echoes this morning moving across northern WY from the northwest Parks into the Bighorn Range. Most of these are very high-based, and dry air near the sfc is keeping most precip from actually reaching the ground. These showers are due to a passing shortwave across western WY north into MT. The shortwave will be mostly through the area by noon, but showers and thunderstorms may linger across the northern Bighorns and northern Johnson County into early afternoon. With daytime heating and instability, some development of strong thunderstorms could build quickly in these areas before sweeping quickly to the northeast by mid- afternoon. Main threat with these storms would be gusty downburst winds due to very dry sfc conditions.

Farther to the south away from the shower activity, the pressure gradient around this system is tighter, which will result in some gusty southwest winds this afternoon. Forecast gusts range from 30 to 40 mph from KRKS across the Green Mountains into Natrona County. This, along with dry air already in place across the state, will lead to near-critical fire weather concerns this afternoon. With most areas still in spring greenup, fuels are less receptive, so Red Flag Warnings will not be posted, but any fires that do spark will still have erratic behavior. Any burning is not advised today.

Once this system moves off this evening, the pattern buckles across the Northern Rockies as a large trough drops down the West Coast. This puts most of WY in favorable ridging, deflecting systems away and allowing temperatures to soar. With H7 temps still forecast to reach 16 to 18C, sfc temps will jump well into the 80s west of the Divide and into the 90s east of the Divide. Models have been trending upwards the past few days, with the latest forecast getting closer to daily record highs, and a couple areas within striking distance of 100 degrees.

Longer term forecast notes the West Coast trough shifting farther east, knocking temperatures back down closer to normal. This will also shift better moisture into western WY, bringing a better chance for daily thunderstorms along the higher elevations of northwestern WY.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1031 PM MDT Thu Jun 4 2026

Mostly SKC skies currently in place this evening. The lower clouds that were expected at KCPR dispersed earlier as the cold front reach the Divide around 03Z. The cold front will reach KRIW shortly after the start of the forecast, washing out after sunrise. Conditions will remain dry through the TAF period. Most terminals will have wind gusts around 20kt by 17Z, becoming light (10kt or less) again by 02Z.

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

RIW WATCHES/WARNINGS/ADVISORIES

None.