Total snow accumulations of 12 to 20 inches (30 to 51 cm). Winds gusting as high as 55 mph.
A major winter storm will spread heavy snow and blowing snow south and east over much of North Central, Central, and Southwest Montana through Sunday.
Snowfall rates through Sunday morning could approach 1 to 2 inches per hour at times, mainly north of Interstate 90 to the Canadian border.
Strong northerly winds through Sunday over the plains will cause white-out conditions. Significant drifting of snow could also make some roads impassable.
Travel could be very difficult to impossible. Blowing snow could significantly reduce visibility to near zero at times. Cold wind chills as low as 15 below zero could also
cause frostbite on exposed skin in as little as 30 minutes.
Thanks to Kenneth Lund for this link