Conditions for a blizzard are possible, says NWS.
Snow in September is not that rare for the area, CNN meteorologist Ivan Cabrera said, but the expected amount is. was the highest snowfall event of the season, "Cabrera said.
Wind, waves and conditions of the white world
Winter weather conditions are expected for parts of Montana, Wyoming and the Dakotas.
"This has the potential to be a historically significant snowfall event early in the season." The National Weather Service in Big Falls, Montana, said.
Sustained winds will be close to the tropical storm force (above 39 mph +) with gusts possible above 60 mph. These winds, combined with forecast snow, will result in white conditions.
With this windy and strong and suddenly cold air interacting with the warmer water of a mountain lake, there is a chance of waves breaking through Flathead Lake. [1