The observer tweeted about it and The National Weather Service responded:
https://twitter.com/andrewbwx/status/851471370399744002
The National Weather Service Billings believes curious turbulence during an otherwise still day was determined likely associated with chairlifts at the Red Lodge Mountain ski area. Pretty cool!
Excellent question! I believe it is the ski lifts on @RedLodgeMntn! Amazing what the radar can see. 🙂 #MTwx https://t.co/0OjD89RXZG
— NWS Billings (@NWSBillings) April 10, 2017