After a gorgeous weekend, the weather is supposed to change drastically tonight though tomorrow with the highest of elevations projected to receive a foot of snow. Details here:

A Winter Storm Warning for elevations above 5500 feet for heavy
snow and blowing snow remains in effect from midnight tonight to 6
am MDT Tuesday.

A Winter Weather Advisory for elevations below
5500 feet for snow and blowing snow remains in effect from
midnight tonight to 6 am MDT Tuesday.

Timing and main impacts: light snow will develop over the
southern portions of southwest Montana after midnight tonight.
Periods of snow will continue through Monday and begin to
taper off Monday night.

Snow accumulations: 3 to 6 inches in the valleys... and 6 to
12 inches in the mountains.

Winds and visibility: visibilities reduced to less than one
half mile at times in snow and blowing snow.

Other impacts: because pavement temperatures are still very
warm... untreated roads will be very icy tonight through
Monday as the colder air moves into the region. These cold
and wet conditions will also stress Young livestock.

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.

Only a few inches of snow expected in the valleys