There is the potential for A LOT of snow with this storm.

... Winter Storm Warning in effect until midnight MDT Friday
night...

The National Weather Service in Great Falls has issued a Winter
Storm Warning for heavy snow... which is in effect until
midnight MDT Friday night. The Winter Storm Watch is no longer in
effect.

* Timing and main impact: light snow will spread north today. The
snow will increase in intensity tonight... with the heaviest snow
is expected late tonight through mid day Friday... before
diminishing late Friday evening. Poor visibilities will hamper
travel.

* Snow accumulations: for the mountains total snow accumulations
of 10 to 20 inches are expected... but isolated amounts around 26
inches are possible near ridge tops. For lower
elevations... generally 5 to 9 inches are expected.

* Winds and visibility: northerly winds at 10 to 20 mph are
expected. The combination of winds and falling snow will reduce
visibilities below one quarter of a mile at times.

* Other impacts: roads will become snow covered and slippery.
Heavy wet snow could cause damage to trees and possible
power outages. Young unprotected livestock could become
stressed.

* Locations affected include: Battle Ridge Pass... Bozeman...
Bozeman Pass... Targhee Pass... West Yellowstone... Big Hole
Pass... Chief Joseph Pass... Dillon... Monida Pass... Ennis...
Norris Hill... Raynolds Pass... Twin Bridges.

Precautionary/preparedness actions...

A Winter Storm Warning for heavy snow means severe winter weather
conditions are expected or occurring. Significant amounts of snow
are forecast that will make travel dangerous. If you must... keep
an extra flashlight... food... and water in your vehicle in case of
an emergency.

For specific Road and travel conditions in Montana... dial 5 1 1.

Source:  Weather Underground