A very moist atmospheric river brought heavy precipitation to the area.  This was followed by an anomalously strong mid-level jet stream that lowered to the surface behind a cold front and resulted in widespread wind damage across the Northern Rockies. Utilities reported over a million dollars in damages from this storm alone. The return interval for the mid-level winds of at least 80 mph occurring, was once every 30 years for early January.

High Wind in LOWER CLARK FORK REGION, MONTANA
From 13-JAN-21 07:00:00 to 13-JAN-21 15:00:00 (MST-7)
Magnitude: 50.00 MG
Property damage: 40.00K
Crop damage: 0.00K
Reported by: AWOS

The Thompson Falls airport observed a peak gust to 58 mph at 10:02 am MST. A trained spotter located 2 miles west-northwest of Belknap observed several 90 year old trees uprooted by the wind. Other reports include: widespread power outages, roof damage in Plains, several buildings damaged in Thompson Falls, 2 ponderosa pine trees down in St. Regis, a fallen tree across a vehicle in De Borgia, a tree down on part of Interstate 90 near mile-marker 22, and multiple large trees across Prospect Road in Thompson Falls.

High Wind in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 13-JAN-21 07:30:00 to 13-JAN-21 14:30:00 (MST-7)
Magnitude: 58.00 MG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Mesonet

Damaging winds were observed from the Missoula Valley to the central Bitterroot Valley. The Missoula International Airport recorded a gust of 59 mph, while a station 2 miles east-northeast of Stevensville registered peak winds up to 67 mph. Multiple large ponderosa and fir trees, as well as powerlines, were reported down across the area.  Close to 10,000 customers were without power at one point during the storm. One electric company reported 38 power poles broken in Missoula County.

High Wind in BUTTE / BLACKFOOT REGION, MONTANA
From 13-JAN-21 08:59:00 to 13-JAN-21 19:30:00 (MST-7)
Magnitude: 70.00 MG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Department of Highways

During this event a Montana Department of Transportation wind sensor, located north of Avon, observed an incredibly extended period of high winds from 9 am to 3 pm MST. Power outages were observed from Ovando to Helmville to Avon and also in the Anaconda area. Peak wind speeds observed during the event included: 80 mph Avon North, 78 mph at MacDonald Pass before the sensor stopped reporting, 67 mph Deer Lodge, and 59 mph Bearmouth.

High Wind in POTOMAC / SEELEY LAKE REGION, MONTANA
From 13-JAN-21 10:00:00 to 13-JAN-21 14:30:00 (MST-7)
Magnitude: 55.00 MG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: RAWS

The Clearwater RAWS reported a peak wind of 63 mph at 11:30 am MST. A private weather station in east Bonner reported a peak wind of 54 mph, and a Montana Department of Transportation sensor at Bearmouth reported a peak wind of 59 mph. Several thousand customers were without power from Condon in the north, through
Seeley Lake, to Bonner and Clinton in the south. Multiple downed trees were reported between Condon and Clearwater Junction. One electric company had to use a helicopter, in tandem with employees hiking in, to replace a power pole near Cramer Creek off of Interstate 90.

High Wind in BITTERROOT / SAPPHIRE MOUNTAINS, MONTANA
From 13-JAN-21 06:00:00 to 13-JAN-21 15:00:00 (MST-7)
Magnitude: 109.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Park/Forest Service

Volunteer groomers for the Chief Joseph cross country trails had to clear an estimated 100 downed trees. They remarked that there was a tree down almost every 100 yards. The U.S. Forest Service reported that a couple of their radio repeaters were blown down in the Bitterroot Mountains. The Little Rock Creek RAWS located at 5500 feet, just south of Lake Como, reported a peak wind of 58 mph. A wind sensor on top of Mount Sentinel (north end of the Sapphire Mountains) recorded a peak wind speed of 125 mph at 10:45 am MST.

High Wind in KOOTENAI/CABINET REGION, MONTANA
From 13-JAN-21 07:00:00 to 13-JAN-21 15:00:00 (MST-7)
Magnitude: 70.00 MG
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Mesonet

This was a very widespread wind event for northwest Montana. Countless trees were either blown down or snapped in half in many locations, causing numerous road blockages. At least 2 dozen trees were blown over along Bull Lake Road, 10 miles north of Heron. One power company reported that they had 51 broken power poles, and experienced extensive power line and cross arm damage during the event. Winds were gusting up to 80 mph at the Zonolite station which is situated 2,000 feet above the Libby area. Wind gusts between 66 and 70 mph were reported in the valleys in the Idaho Panhandle and based on the fact that trees were down all over Lincoln County, these wind speeds are a good estimate of what happened. At least 15,000 people were without power by mid-day on the 13th, and some outages lasted through the following weekend. One utility that covers part of the Idaho Panhandle and northwest Montana reported over one million dollars in damages.

High Wind in WEST GLACIER REGION, MONTANA
From 13-JAN-21 07:00:00 to 13-JAN-21 15:00:00 (MST-7)
Magnitude: 56.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winds gusted between 50 and 65 mph in the lower elevations, causing mature trees to fall over or snap in half.  In Martin City, a mature tree snapped three feet from the ground and destroyed a small outbuilding. Power lines were reported down across Highway 83 about 4 miles northwest of Swan Lake. On top of Mount Aeneas, located in the Swan Range at nearly 7500 feet, winds peaked at 101 mph. The winds forced one ski resort to close the top half of their mountain. Several thousand people were without power, and the West Glacier School closed because of the high winds.

High Wind in FLATHEAD/MISSION VALLEYS, MONTANA
From 13-JAN-21 07:00:00 to 13-JAN-21 15:00:00 (MST-7)
Magnitude: 56.00 MG
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Mesonet

Multiple locations in both the Flathead and Mission valleys reported frequent gusts between 50 and 65 mph. An employee with the Montana Department of Transportation, who had lived in the area for over 40 years, remarked that he had never seen such widespread tree damage before. Many primary and secondary roads were blocked or closed for a time during the windstorm due to downed trees or powerlines down. One power company reported over 16,000 customers without power with 153 distinct outages from Libby to Essex at 3 pm MST on the 13th. Power was not restored for some people until 5 days later. A large pine tree crushed a pickup truck and damaged another vehicle on Elk Park Road in Columbia Falls.