Over a period of 5 days, a large, complex and dangerous storm system moved into Idaho and western Montana. This storm had a number of factors that interacted to produce a wide range of snowfall totals, precipitation types and temperature ranges. First, a very cold arctic air mass moved out of Canada into eastern Montana and then filtered across the divide into western Montana. Second, a large Pacific storm moved in from the west, this system had an abundant moisture feed, as well as jet stream support. Hazardous travel caused school closures in the Missoula area for two consecutive days, a very rare occurrence.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 6 miles southeast of Clinton, where 13 inches of snow was measured.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:38:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 9 miles southeast of Clinton, where 12.7 inches were measured.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:45:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snow was reported 12 miles southeast of Clinton, where 15.5 inches of snowfall was reported.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:50:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 14 miles southeast of Clinton, where 13.5 inches were measured.

Heavy Snow in FLATHEAD/MISSION VALLEYS, MONTANA
From 15-JAN-12 13:00:00 to 19-JAN-12 03:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A spotter 1 miles southwest of Columbia Falls measured 15.5 inches of snow.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 00:35:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 8 miles east of Missoula, where 10.7 inches were measured.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 04:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snow was reported 4 miles east of Florence where 18 inches were measured.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 05:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A snowfall storm total of 14 inches was measures 6 miles south southest of Missoula.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 06:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The storm total snowfall measured 2 miles north of Missoula was 14 inches.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 00:42:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 1 mile east of Missoula, where 13.2 inches were measured.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 06:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Snowfall of 16 inches was measured in Missoula by a NWS employee.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 06:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

The storm total measured 5 miles west northwest of Missoula was 10.5 inches.

Heavy Snow in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 00:42:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 3 miles east of Missoula, where 15 inches were measured.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 18-JAN-12 08:00:00 to 19-JAN-12 08:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A 24 hour snowfall total of 16 inches was measured in Condon.

Heavy Snow in LOWER CLARK FORK REGION, MONTANA
From 16-JAN-12 14:00:00 to 17-JAN-12 13:59:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

The Department of Highways reported 12 inches of snow on I-90 6 miles northwest of Saltese and 18 inches of snow at Lookout pass.

Ice Storm in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 19-JAN-12 16:00:00 to 19-JAN-12 17:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Freezing rain was reported 3 miles east of Florence, forming a crust on the snow and the ground. Roads were slick.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:08:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported in Clinton, where 15.2 inches were measured.

Heavy Snow in POTOMAC / SEELEY LAKE REGION, MONTANA
From 15-JAN-12 11:00:00 to 19-JAN-12 01:25:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Heavy snowfall was reported 4 miles east southeast of Clinton, where 16.8 inches were measured.