After being in cold Arctic air, overrunning warm and moist air caused moderate to heavy snow and produced poor visibilities and very slick roads.

Heavy Snow in BITTERROOT / SAPPHIRE MOUNTAINS, MONTANA
From 14-DEC-16 18:00:00 to 15-DEC-16 14:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Moderate to heavy snow caused slick roads and low visibility during this event. Total snow amounts include 13 at Lost Trail, 10.5 five miles east of Sula, 9.5 fourteen miles northeast of Sula, and near 6 west of Lolo.

Heavy Snow in LOWER CLARK FORK REGION, MONTANA
From 14-DEC-16 21:00:00 to 15-DEC-16 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

A combination of moderate to heavy snow, snow-covered roads, and low visibility created high impact to travel. The poor visibilities were caused by vehicles stirring up the very light snow on the surface. Chains were required for US-93 to Evaro Hill during the morning commute on the 15th. Total snow amounts: 5.3 at Alberton, 4 at Haugan and Evaro Hill, and 3 at Thompson Falls.

Heavy Snow in BUTTE / BLACKFOOT REGION, MONTANA
From 14-DEC-16 21:00:00 to 15-DEC-16 17:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A combination of moderate to heavy snow, snow-covered roads, and low visibility created high impact to travel. The poor visibilities were caused by vehicles stirring up the very light snow on the surface. The snow fell heavy enough that there was barely one lane on Interstate 90 at times. Snow amounts: 9 Deer Lodge, 7 Georgetown Lake, 6 Elliston, and 3 Anaconda and Ovando.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-DEC-16 01:00:00 to 15-DEC-16 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

A combination of moderate to heavy snow, snow-covered roads, and low visibility created high impact to travel. The poor visibilities were caused by vehicles stirring up the very light snow on the surface. Multiple vehicle slide-offs were reported, and there was a snow plow that slid off the road near Bonner. Total snow amounts: 10 Lindbergh Lake, 6.4 Seeley Lake, 6 Bonner and Clinton, and 4 Greenough Hill.

Heavy Snow in FLATHEAD/MISSION VALLEYS, MONTANA
From 15-DEC-16 02:00:00 to 15-DEC-16 20:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Between 8 and 14 inches of heavy snow fell from the Polson area east to Highway 35 on the east side of Flathead Lake. Also a combination of moderate to heavy snow, snow-covered roads, and low visibility created high impact to travel in the Mission Valley. The poor visibilities were caused by vehicles stirring up the very light snow on the surface. Other snow amounts include 4 NW of St. Ignatius, 2.4 at Glacier Park International Airport and 2.2 at Ronan.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-DEC-16 06:00:00 to 15-DEC-16 14:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A combination of moderate to heavy snow, snow-covered roads, and low visibility created high impact to travel. The poor visibilities were caused by vehicles stirring up the very light snow on the surface. Total snow amounts include 13 at Darby and 2 miles WNW of Stevensville, 8 at Hamilton, 7.5 3 miles east of Florence, 7 in the South Hills of Missoula, and 6.3 at the Missoula International Airport.