A storm system moved from southern California into the northern Rockies and northern Plains.  Very stable conditions ahead of the storm system created several days of very dense fog from the 18th through the 22nd of January.  This fog created significant delays of commercial and general aviation flights, as well as emergency medical flights having to be grounded.  The freezing fog and rime ice, and some light freezing rain accumulated on power lines, causing the lines to snap starting on the 20th and 21st of January.  As the storm approached, snow quickly spread from south to north across the area on the afternoon of the 22nd.  When the main cold front finally moved through late on the 22nd and the 23rd, the winds switched from the east to the north and northwest with speeds from 25 to 40 mph, resulting in blizzard conditions.  Widespread road closures and whiteout conditions kept power crews from being able to restore power, and many residents were without power until January 25th and 26th. Snowfall measurements were difficult to obtain east of Valley and Garfield counties due to the strong winds.

Freezing Fog in WESTERN ROOSEVELT, MONTANA
From 19-JAN-10 05:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 15.00K
Crop damage: 0.00K
Reported by: State Official

State DES reported there was extensive electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from NorVal and Sheridan Electric.  Commercial and general aviation interests were also impacted with flights unable to come in or fly out of the Wolf Point and Poplar Airports.

Freezing Fog in EASTERN ROOSEVELT, MONTANA
From 18-JAN-10 23:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 10.00K
Crop damage: 0.00K
Reported by: State Official

State DES reported there was extensive electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from Sheridan Electric.

Freezing Fog in SHERIDAN, MONTANA
From 18-JAN-10 23:00:00 to 23-JAN-10 22:30:00 (MST-7)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: State Official

State DES reported there was extensive electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from Sheridan Electric.

Freezing Fog in DANIELS, MONTANA
From 19-JAN-10 05:00:00 to 23-JAN-10 22:30:00 (MST-7)
Property damage: 40.00K
Crop damage: 0.00K
Reported by: State Official

State DES reported there was extensive electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from NorVal and Sheridan Electric.

Freezing Fog in NORTHERN VALLEY, MONTANA
From 19-JAN-10 15:00:00 to 23-JAN-10 22:30:00 (MST-7)
Property damage: 75.00K
Crop damage: 0.00K
Reported by: State Official

State DES reported there was extensive electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from NorVal Electric.

Winter Storm in CENTRAL AND SOUTHERN VALLEY, MONTANA
From 22-JAN-10 17:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Snowfall estimates ranged from seven to eight inches in most locations before the wind hit the area. 14 inches were estimated 5 SW of Hinsdale the morning of the 24th.

Winter Storm in PETROLEUM, MONTANA
From 22-JAN-10 12:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotters estimated six to eight inches of snow. Ground blizzards were also observed.

Freezing Fog in CENTRAL AND SOUTHERN VALLEY, MONTANA
From 19-JAN-10 15:00:00 to 24-JAN-10 23:30:00 (MST-7)
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Freezing fog lasted for nearly five days, causing commercial and general aviation delays and cancellations, as well as significant damage to power poles.   State DES was able to get damage estimates from NorVal Electric.

Freezing Fog in WIBAUX, MONTANA
From 19-JAN-10 11:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 8.00K
Crop damage: 0.00K
Reported by: State Official

Dense freezing fog impacted the area with electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from Golden West Electric and State DES.

Freezing Fog in RICHLAND, MONTANA
From 19-JAN-10 05:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Freezing fog lasted for four days, causing commercial and general aviation delays and cancellations.

Winter Storm in CENTRAL AND SE PHILLIPS, MONTANA
From 22-JAN-10 19:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Six to eight inches of snowfall were commonly reported across the zone. Blowing snow reduced the visibility to less than a quarter of a mile 35 S of Malta.

Winter Storm in LITTLE ROCKY MOUNTAINS, MONTANA
From 22-JAN-10 19:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter 1 SSE Zortman estimated 15 inches of snowfall.

Freezing Fog in MCCONE, MONTANA
From 19-JAN-10 11:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 2.00K
Crop damage: 0.00K
Reported by: State Official

Dense freezing fog impacted the area with electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from McCone Electric and State DES.

Winter Storm in GARFIELD, MONTANA
From 22-JAN-10 12:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotters reported eight to ten inches of snow. Blowing snow reduced visibility to less than a quarter of a mile at times. Some roads were drifted shut.

Freezing Fog in CENTRAL AND SE PHILLIPS, MONTANA
From 19-JAN-10 11:00:00 to 23-JAN-10 22:30:00 (MST-7)
Property damage: 4.00K
Crop damage: 0.00K
Reported by: State Official

Dense freezing fog impacted the area with electrical pole damage across the area due to rime ice accumulation. Dollar amounts were from Big Flat Electric and State DES.

Freezing Fog in DAWSON, MONTANA
From 19-JAN-10 11:00:00 to 23-JAN-10 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Freezing fog lasted for four days, causing commercial and general aviation delays and cancellations.

Winter Storm in NORTHERN PHILLIPS, MONTANA
From 22-JAN-10 18:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter estimated new snowfall of 6 inches with some blowing and drifting.

Winter Storm in DANIELS, MONTANA
From 22-JAN-10 17:00:00 to 24-JAN-10 08:27:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotter estimated seven inches of new snowfall along with drifting snow.