Winter Storm Warning issued December 18 at 2:05AM MST until December 18 at 11:00PM MST by NWS Missoula MT

* WHAT…Heavy snow expected. Likelihood of major impacts from 5 to
10 inches of snow above 5,000 feet, including Marias Pass, is 90
percent. The likelihood of extreme impacts from 10 to 18 inches of
snow is 30 percent. Winds gusting as high as 60 mph. Total snow
accumulations of 1 to 4 inches below 5,000 feet.

* WHERE…Bad Rock Canyon, Essex, Marias Pass, Highway 83 Bigfork to
Swan Lake, and Polebridge.

* WHEN…Until 11 PM MST this evening.

* IMPACTS…Visibilities may drop below 1/4 mile due to falling and
blowing snow. The strong winds and weight of snow on tree limbs
may down power lines and could cause sporadic power outages.
Periods of whiteout conditions are expected across Marias Pass and
will make travel treacherous and potentially life-threatening.