MacDonald Pass on US 12 in Montana the morning of Friday, September 15, 2017.
The Montana Department of Transportation says that people driving through mountain passes should be alert for conditions ranging from slush to ice to snow.
Rain at lower elevations and snow at higher elevations is expected to continue through Saturday.
Temperatures are expected to dip into the 30s tonight for most areas, and even below freezing for some spots.
The National Weather Service in Great Falls has issued a Winter Storm Warning for Cascade County, Lewis and Clark County, Southern Rocky Mountain Front, Judith Basin County, Jefferson County, Broadwater County, and Meagher County until noon Saturday.
Locations include all high elevations above 5500'.
Total accumulation at pass levels expected 3-6" with high amounts of 5-10" above pass level.
Visibility reduced to a 1/2 a mile or less with wind gusts up to 35 mph.
Slushy and snowy conditions will cause travel impacts over mountain passes tonight and tomorrow morning.
Below normal temperatures
With a dip in the jet stream, cooler temperatures will stick around into the weekend.
Temperatures will be 10°-30° below normal this weekend.
Comment: See also: Early snowfall at Rogers Pass, Montana