A strong jet aloft with a core wind speed of 170+ mph helped drive a fast moving cold front which brought high winds to many locations across the Northern Rockies. Snow above 5500 feet led to winter storm conditions for high passes and back-country users.  Lower atmosphere standardized wind anomalies ranged between +3 and +4 for this time of year, indicating a once-in-10-year wind event.

High Wind in KOOTENAI/CABINET REGION, MONTANA
From 17-NOV-15 21:00:00 to 18-NOV-15 03:00:00 (MST-7)
Magnitude: 57.00 MG
Reported by: RAWS

Zonolite RAWS reported wind gusts of over 50 mph for 5 hours, with a peak gust of 66 mph. The strength of winds in valleys was likely not quite to this level, but based on damages, localized mountain waves likely caused winds of nearly this magnitude in valleys overnight.

High Wind in KOOTENAI/CABINET REGION, MONTANA
From 17-NOV-15 21:00:00 to 18-NOV-15 03:00:00 (MST-7)
Magnitude: 52.00 EG
Property damage: 60.00K
Reported by: Emergency Manager

Power outages affected many communities in Lincoln County. Trees took out power lines and a 4 power poles.  Several pine, elm and spruce trees were blown down and blocking area roads. Prior rainfall contributed to helping push the trees over. One hotel had severe roof damage, and a few houses lost their metal roof, although these roofs were old and reportedly not up to code. Debris was widespread in county. Cell service was down from 7 pm 11/17 through 4 pm 11/18. In Troy, they lost power overnight. The winds in Libby were worse than measured at the nearby Libby airport.

High Wind in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 17-NOV-15 20:00:00 to 18-NOV-15 05:00:00 (MST-7)
Magnitude: 51.00 MG
Property damage: 100.00K
Reported by: ASOS

At 1:30 am, the Missoula International Airport ASOS reported a wind gust of 59 mph. Tens of Ponderosa Pine and other deciduous trees in town were blown down overnight, and several limbs were blown off. A trained weather spotter estimated 60+ mph winds in southern Missoula around 1 am 12/18, additionally reporting roof damage to house due to 8-inch diameter limb falling off tree. An apartment complex in the hills of southern Missoula sustained heavy roof damage as well.

High Wind in MISSOULA / BITTERROOT VALLEYS, MONTANA
From 17-NOV-15 20:00:00 to 18-NOV-15 05:00:00 (MST-7)
Magnitude: 57.00 MG
Crop damage: 0.00K
Reported by: AWSS

A personal weather station a few miles southeast of Lolo, MT measured a 66 mph wind gust at 3600 ft around 8pm on 12/17. Trees downed power lines, which cut out power to 3500 people in Ravalli county. The power returned during the afternoon on 12/18.

High Wind in BUTTE / BLACKFOOT REGION, MONTANA
From 17-NOV-15 23:00:00 to 18-NOV-15 05:00:00 (MST-7)
Magnitude: 52.00 MG
Property damage: 50.00K
Reported by: Public

The public reported 60 mph winds in Anaconda Overnight. A personal weather sensor between Anaconda and Butte reported a 52 mph gust. One home in Anaconda sustained siding damage, while another lost part of a metal roof (the roof was not well-constructed). Emergency managers reported a street light blown down in Anaconda, with multiple trees down in the area. Additionally, a tree smashed a parked car in Butte, causing thousands of dollars of damage.

Winter Storm in BUTTE / BLACKFOOT REGION, MONTANA
From 18-NOV-15 05:30:00 to 18-NOV-15 08:00:00 (MST-7)
Reported by: Department of Highways

Snow combined with high winds over Homestake Pass lead to a traffic jam of semi-trucks during the early morning hours as road conditions became hazardous. Over 30 semis were stuck at a time, with most issues due to failure to chain-up.

Winter Storm in WEST GLACIER REGION, MONTANA
From 17-NOV-15 20:00:00 to 18-NOV-15 08:00:00 (MST-7)
Property damage: 10.00K
Reported by: Department of Highways

Montana road crews reported 8 to 10 inches of snow overnight at Marias pass, with heavy snow at times. Lower elevations, such as West Glacier, MT reported 2 to 3 inches. Multiple trees were blown down over both lanes of US-2 near Essex, MT. High elevation RAWS sites reported winds gusts in the 50 mph range, causing dangerous back-county conditions for hunters.

Winter Storm in BITTERROOT / SAPPHIRE MOUNTAINS, MONTANA
From 17-NOV-15 18:00:00 to 18-NOV-15 04:00:00 (MST-7)
Reported by: Department of Highways

Snowfall intensity increased during the evening at Lolo Pass with winds gusting to an estimated 50+ mph. Roads crews reported snow-covered roads with high winds overnight, with the Deer Mountain RAWS at 7300 ft reporting 63 mph gusts in the early morning hours.

Winter Storm in POTOMAC / SEELEY LAKE REGION, MONTANA
From 17-NOV-15 20:00:00 to 18-NOV-15 06:00:00 (MST-7)
Reported by: RAWS

Light snow at high elevations combined with winds gusting 50-84 mph made for hazardous back-country conditions for hunters. The Point 6 RAWS at 8000 ft reported a wind gust of 84 with light snow, while the 6250 ft N Fork Elk Creek SNOTEL also reported light snow.

High Wind in FLATHEAD/MISSION VALLEYS, MONTANA
From 17-NOV-15 17:00:00 to 18-NOV-15 05:00:00 (MST-7)
Magnitude: 39.00 ES
Property damage: 25.00K
Reported by: Trained Spotter

A trained spotter measured a wind gust of 52 mph in the Flathead Valley around 7pm. A personal weather sensor measured a wind gust of 49.3 miles per hour on the north shore of Flathead Lake, near the Bigfork, MT.  Estimated sustained winds were 45 mph based on damages. That evening, power was lost by about 8000 customers, as over a dozen power poles were blown down.

High Wind in LOWER CLARK FORK REGION, MONTANA
From 17-NOV-15 18:00:00 to 18-NOV-15 02:00:00 (MST-7)
Magnitude: 39.00 ES
Property damage: 10.00K
Reported by: RAWS

For 9 hours, from 4pm 12/17 - 1am 12/18, the Pardee RAWS recorded gusts of around 40 mph, with a peak gust of 45 mph at 10pm. Sustained winds in the valleys were estimated at 45 mph based on damages. The relatively uncommon SSE wind direction likely contributed to tree damage with this storm. Five large trees fell near Alberton, MT, one which briefly blocked an interstate lane overnight. Additionally, Superior, MT schools were cancelled on 12/18 due to power outages.