The big pattern change that has been advertised for the last several days is occurring this weekend. A large cold trough moving onto the west coast will dominate the western states through much of the week.
The first chart is the 500mb analysis Sunday morning followed by the forecast 500mb chart for Wednesday morning.
Local mountains will see significant snow this week, possibly totaling 1-2 feet. In Star Valley precipitation should turn to all snow by Tuesday. Temperatures will remain in the 30s in the valley during the daytime hours from Tuesday on, so at least some accumulation is likely, particularly in the higher locations.
The Riverton Forecast Office has issued a comprehensive discussion on the upcoming weeks weather.