The Cheyenne Office of the National Weather Service says 70 mph winds,golf-ball size hail, and even a brief tornado are possible on Sunday.

Flash flooding is also possible in some areas (areas in green on the map on left below).

The weather service issued the following situation report on Sunday morning:

".-Severe thunderstorms will be possible across much of the region later this afternoon and evening.

- Main hazards will be large hail up to golf-ball size, 60-70 mph winds, and a brief tornado will be possible. "

Flooding -National Weather Service
National Weather Service