A strong upper level jet and Pacific moisture combined with arctic air stalled over northwest Montana, led to multiple hours of heavy snow rates and difficult travel. Strong arctic winds brought wind chills down to 70 below zero along the Divide and dangerous wind chills across western Montana. A flash freeze and blowing snow were observed across west-central Montana when the arctic cold front pushed through overnight. As skies cleared, extreme cold to 50 below zero were observed along the Divide.

Extreme Cold/Wind Chill in BUTTE / BLACKFOOT REGION, MONTANA
From 21-DEC-22 11:00:00 to 22-DEC-22 09:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Temperatures fell between 35 and 43 below zero. Butte dropped to 40 below zero. Discovery Ski Area closed due to extreme cold.

Winter Storm in BUTTE / BLACKFOOT REGION, MONTANA
From 20-DEC-22 23:50:00 to 21-DEC-22 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Snow, blowing and drifting snow, and dangerous wind chills impacted areas along US Highway 12 and Interstate 90, prompting MDT to declare severe driving conditions. Numerous slide offs occurred between Garrison Junction and Deer Lodge, where visibility below one quarter of a mile was observed by area spotters and mesonets. Wind chills dropped between 30 and 50 below as north-northeast winds reached 20 to 30 mph and temperatures dropped in the teens to low 20s below zero. MacDonald Pass reported a wind chill of 60 below zero.

Winter Storm in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 21-DEC-22 01:00:00 to 21-DEC-22 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Roadways experienced a flash freeze, and blowing and drifting snow as the arctic front arrived, which led to MDT declaring severe driving conditions. Numerous schools closed due to weather on December 21st.

Extreme Cold/Wind Chill in POTOMAC / SEELEY LAKE REGION, MONTANA
From 21-DEC-22 17:30:00 to 22-DEC-22 10:15:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Low temperatures on December 22nd reached 49 below in Potomac, and 41 below in Seeley Lake and in Clearwater Junction. Extreme cold closed Snowbowl Ski Area.

Winter Storm in WEST GLACIER REGION, MONTANA
From 20-DEC-22 11:00:00 to 21-DEC-22 08:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Heavy snow and east-northeast winds of 20-30 mph with gusts to 45 mph led to periods of whiteout conditions on US Highway 2 east of West Glacier. MDT and the Essex COOP reported 29 inches of snowfall. 14 inches of snow was measured in West Glacier.

Extreme Cold/Wind Chill in KOOTENAI/CABINET REGION, MONTANA
From 21-DEC-22 20:00:00 to 22-DEC-22 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Temperatures fell between 20 and 41 below. Notable observations include: 41 below Olney, 39 below Yaak, and 31 below in Libby.

Extreme Cold/Wind Chill in WEST GLACIER REGION, MONTANA
From 21-DEC-22 08:00:00 to 22-DEC-22 11:14:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Widespread wind chills of 40 to 55 below zero were observed. Snowslip Mountain in Glacier National Park recorded a wind chill of 70 below zero. Temperatures fell to 49 below at Marias Pass, 47 below in Polebridge, 36 below in Hungry Horse, and 34 below in West Glacier.

Extreme Cold/Wind Chill in LOWER CLARK FORK REGION, MONTANA
From 22-DEC-22 06:00:00 to 22-DEC-22 12:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind chills reached 31 below in Thompson Falls and as low as 41 below in the mountains (Mullan Pass). Temperatures fell between 15 and 27 below.

Winter Storm in LOWER CLARK FORK REGION, MONTANA
From 20-DEC-22 11:00:00 to 21-DEC-22 01:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MDT declared severe driving conditions on Interstate 90 from Tarkio to Lookout Pass as snowfall rates up to 2 inches per hour were observed. Wind gusts of 30 to 35 mph led to areas of blowing and drifting snow in the mountains. Between 8 to 14 inches of snow fell along the Highway 200 corridor, which led to cancellations of area schools on December 22.

Winter Storm in KOOTENAI/CABINET REGION, MONTANA
From 20-DEC-22 08:00:00 to 20-DEC-22 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MDT reported snowfall rates in excess of 1 inch per hour in Libby for 9 consecutive hours. Trained spotters in Libby reported 14 inches of snow. Snow, blowing and drifting snow led to whiteout conditions on US Highway 2 and 93.

Winter Storm in FLATHEAD/MISSION VALLEYS, MONTANA
From 20-DEC-22 11:00:00 to 21-DEC-22 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Widespread heavy snowfall, with rates up 2 inches per hour, was observed on December 20th. Snowfall accumulations of 5 to 12 inches was reported, with Bigfork receiving 14 inches. Arctic north-northeast winds of 30 to 50 mph led to widespread blowing and drifting snow on December 21st. Lake County officials declared emergency travel as area roadways became impassable. Flathead County closed Hodgson Road due to drifting snow. Numerous schools announced closures on December 21st.

Extreme Cold/Wind Chill in FLATHEAD/MISSION VALLEYS, MONTANA
From 21-DEC-22 11:00:00 to 22-DEC-22 11:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind chills dropped to 30 to 40 below zero across the Flathead Valley and to 30 below in the Mission Valley on the December 21st. Temperatures dropped to 34 below in Kalispell (7th coldest on record) and Hot Springs. Creston dropped to 35 below zero. Several thousand people lost power during the morning of December 21st across the Flathead Valley.

Extreme Cold/Wind Chill in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 21-DEC-22 21:25:00 to 22-DEC-22 13:40:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Wind chills fell to 38 below zero in Missoula as sustained east winds of 15 to 25 mph were observed. Notable low temperatures include: 27 below Frenchtown, 26 below Stevensville, 24 below Hamilton, and 19 below Missoula.

Winter Storm in BITTERROOT / SAPPHIRE MOUNTAINS, MONTANA
From 20-DEC-22 14:00:00 to 21-DEC-22 08:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

MDT reported a flash freeze, blowing and drifting snow, as the arctic front arrived on December 21st. 12 inches of snow was reported at Lost Trail Pass, with at least 13 inches accumulating at Lolo Pass.

Extreme Cold/Wind Chill in BITTERROOT / SAPPHIRE MOUNTAINS, MONTANA
From 21-DEC-22 20:00:00 to 22-DEC-22 13:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Lost Trail Ski Area closed on December 22 as wind chills dropped to 47 below zero. Widespread wind chills of 40 below or colder were observed across mountain sites. Temperatures dropped between 20 and 30 below, with the Skalkaho summit Snotel hitting 34 below.