textproduct: Western and Central Wyoming

KEY MESSAGES

- Scattered showers and thunderstorms are forecast (30 to 70 percent) roughly from Alpine to Riverton to Casper and north through 8PM this evening. The greatest coverage is expected across the Bighorn Basin and Yellowstone National Park.

- Expect high temperatures to be in the upper 50s to low 70s across the area with gusty 25 to 40 mph winds.

- Warmer temperatures are forecast this upcoming week with highs in the 70s and 80s by Tuesday. Afternoon shower and thunderstorm chances exist Monday and Thursday, mainly along and east of the Continental Divide.

DISCUSSION

Issued at 1235 AM MDT Sun May 31 2026

As expected, areas west of a Cody-to-Rock Springs line had the highest amounts of precipitation since 7am Saturday ranging between 0.15" to 0.70". Roughly add another 0.20" to include the precipitation that was occurring earlier Saturday morning/Friday night. Showers will be mainly confined to western and northern portions of the CWA early this morning as the upper low continues to slowly track toward the northeast. An area of showers will continue over southern portions of the Jackson Valley/northern portions of Star Valley and into the Upper Green River Basin, with additional showers from southern MT moving over YNP and the rest of the Jackson Valley around 10Z this morning. Showers and thunderstorms developed over far northern portions of Johnson County around 05Z and have been backbuilding toward Kaycee through 06Z. This activity will continue to track westward over the Bighorns through 12Z this morning.

Showers will become concentrated over northern portions after sunrise this morning as the upper low moves over the Black Hills and pivots over far eastern MT through the day. Any showers over the Wind River Basin and Natrona County will be isolated and conditions will remain dry elsewhere in the CWA. Precipitation amounts will be much lower with these showers, ranging between 0.10" and 0.20" through the day. Snow levels will stay around 9000-10000ft, with lower levels around 7500 over YNP and the Absarokas. A brief heavy downpour cannot be ruled out, especially in the Bighorn Basin, but is not expected. Precipitation will end from west to east through the evening. Otherwise, wind will be the main feature today with gusts of 25 to 35 mph developing over areas west of the Divide after 15Z and spread into Natrona County by 18Z. Similar winds will develop near Dubois and Crowheart after sunrise and spread down the basin toward Riverton. These winds will decrease across the area in the evening, lingering the longest in the Wind River Basin (which should finally end around 07Z Monday).

Isolated showers and thunderstorms will be possible Monday, as a shortwave moves over the Cowboy State. Winds aloft will be southwesterly as a trough develops over the Northern Rockies from the remnants of the upper low. Most of the convection looks to be isolated across the CWA, occurring along and east of a line from the Bighorns to western Sweetwater County. An additional area of isolated showers will be possible over far northwestern portions. Wind gusts up to 45 mph will be the main threat, as instability will be pretty modest between 200-500 J/kg. Tuesday and Wednesday look to stay mainly dry, with west-southwest winds aloft keeping any potential convection over far eastern portions of the state. Showers and thunderstorms will be possible again Thursday, with dry conditions returning for Friday. Temperatures will be above normal from Tuesday to Friday, with highs in the upper 70s into the 80s. Hot and dry conditions look to return for next weekend.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 519 AM MDT Sun May 31 2026

Most terminals will be VFR through at least 12Z Monday as a weather system exits Wyoming today. The exception terminals are KJAC and KCOD, where periods of MVFR ceilings are forecast for a few hours prior to 18Z. Rain and/or thunderstorms are expected across portions of western and northern Wyoming today, impacting KJAC, KCOD, KCPR, and KWRL. Thunderstorm will generally be more scattered in the area of KJAC, KCPR, and KCOD so opt'd for PROB30 groups at this time. Confidence is around 60 percent in prevailing thunderstorms at KCOD during the afternoon. All rain and/or thunderstorm chances come to an end, at the latest, by 02Z. MVFR flight conditions and gusty winds are expected in and around any thunderstorm. All other terminals are forecast to remain dry. Mountain obscurations can be expected across western and northern Wyoming around showers and thunderstorms.

Winds will begin to increase above 10kts at all terminals after 15Z and be between 10kts and 15kts through sunset. Frequent wind gusts of 20kts to 30kts are anticipated at KCPR, KCOD, KRIW, KPNA, and KWRL through the day today. KRKS will see the strongest wind gusts of 30kts to 40kts. Winds decrease to below 11kts at all terminals by 05Z.

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.