Winter Storm and High Wind in Montana, November 17 to 18, 2015

Name: Winter Storm and High Wind in Montana, November 17 to 18, 2015
Start: 2015-11-17T17:00
End: 2015-11-18T08:00
Location: Montana

November 17 to 18, 2015 · NWS MSO · 11 events in 8 counties and zones

Where it happened

Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: $255,000
Crop damage: None recorded
Events: 11

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS MSO wrote it up.

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.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Missoula, MT wrote its last area forecast discussion before the first event at Nov 17, 2:45 PM MST, 2 hours 15 minutes earlier.

Area forecast discussion, Nov 17, 2:45 PM MST, 2 hours 15 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
245 PM MST TUE NOV 17 2015

...Damaging winds for portions of the Northern Rockies this
evening and overnight...
...Potential development of snow bands Wednesday morning...

.DISCUSSION...

Damaging wind gusts remain on-track to impact the Northern
Rockies this afternoon through Wednesday morning. Some locations
that are of particular concern will be I-90 Deer Lodge to
Anaconda, the Bitterroot Valley, Highway 12 east of Garrison
Junction to MacDonald Pass, Homestake Pass, and Georgetown Lake
and vicinity, where wind gusts may briefly exceed 70 mph. Winds of
this magnitude will be perilous for high-profile vehicles, damage
to mature trees, significant damage to wooden power poles, and
damage to outdoor items sent airborne. Gust to 60 mph remain
possible for much of the rest of Northern Rockies, particularly
high valleys, mountain ridges, and mountain passes. A strong cold
front moving across the region overnight tonight will further
concentrate winds as wind direction shifts from southwest to
northwest.

Other impacts from this system, will be snow and blowing snow.
Snowfall has already occurred this morning, but is now confined
to the highest elevations with the rising snow levels. However,
snow levels are expected to crash back down to valley floors this
evening as the strong cold front pushes through. Mountain passes,
especially, Marias Pass will see periods of blizzard conditions
this evening when combining the wind and snow. Near zero
visibility and snow covered roads will cause hazardous driving
conditions tonight. Lolo and Lost Trail Passes will also
experience these conditions, though the winds are not expected to
be as strong. Therefore winter weather warnings remain in place
through the night. Valleys will also see a burst of snow overnight
along the front, although accumulations at this time, are expected
to be minimal.

One place to keep an eye on overnight and Wednesday morning, will
be MacDonald and Homestake Passes, as strong winds are forecast
to impact those regions, as well as periods of brief heavy snow.
Advisories/warnings in these areas may need to be revisited.

The potential for snow impacts will continue through the day on
Wednesday. With the rush of the colder airmass behind the front,
and the development of a northwesterly flow, snow banding is a
real possibility. Locations with the highest potential for seeing
snow bands will be the mountains and valleys along and south of
the I-90 Corridor. Expect rapidly changing road/visibility
changes due to the relatively narrow nature of the snow bands.
Some locations could see a few inches of snow, with areas a short
distance away, only relieving a trace of snow. After Wednesday,
expect light widespread snow showers to occur through Friday for
all of the Northern Rockies.

A relatively cold airmass is expected to move over the Northern
Rockies Friday night through Sunday. Models suggest that cold air
will settle into the area valleys and begin a period of daylong
temperature inversions. These inversions are likely to strengthen
through early next week, when high pressure will move overhead.
Freezing fog and low stratus will begin to be a possibility.
Temperature inversions will also have implications concerning air
quality around the region, particularly for prone poor winter air
quality valleys, such as Seeley-Swan, Missoula, Salmon, and low
elevations of Lincoln County.

Long range models suggest that a very broad and very complex
winter storm system will impact the Northern Rockies around the
middle of next week. Currently, there is modest confidence in the
timing and breadth of this system. Potential impacts from this
system include: difficult travel around the region due to snow,
blowing snow, and low visibility, as well as danger to humans and
animals from wind chill below zero. Get ready for winter.

&&

.AVIATION...Strong/damaging winds are still expected to impact
all aviation sites this evening and overnight. Snow levels will
be crashing to valley floors this evening once the sunsets and the
cold front pushes through. Lowering ceilings and mountain
obscurations can be expected for the rest of the evening through
tonight. Blizzard conditions can be expected as the cold front
makes it's way from a northwest to southeast direction. The strong
winds and snowfall will lower visibilities for a short period of
time. Strong mountain waves are anticipated behind the front for
northwest Montana, south through the Bitterroot valley. Valleys
could see winds gusts over 50kt for a period of time, with the
mountains seeing 50kt and greater sustained winds. The strongest
winds are expected to be between 0600Z-1200Z.

&&

.AIR STAGNATION...

High pressure over the Northern Rockies this weekend through early
next week will have the potential to create daylong temperature
inversions and stagnant airmasses within valleys across the
region. In particular, Seeley-Swan Valley, Missoula Valley, low
elevations of Lincoln County, and around Salmon Idaho will be most
prone to stagnant air.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Warning until 11 AM MST Wednesday ABOVE 5500 FEET
     for the Bitterroot/Sapphire Mountains...Potomac/Seeley Lake
     Region.

     High Wind Warning from 5 PM this afternoon to 11 AM MST
     Wednesday Butte/Blackfoot Region.

     High Wind Warning from 5 PM this afternoon to 11 AM MST
     Wednesday Flathead/Mission Valleys...Missoula/Bitterroot
     Valleys.

     High Wind Warning until 11 AM MST Wednesday Lower Clark Fork
     Region.

     Wind Advisory until 11 AM MST Wednesday Kootenai/Cabinet Region.

     Winter Storm Warning until 11 AM MST Wednesday ABOVE 5000 FEET
     for the West Glacier Region.

ID...Winter Storm Warning until 11 AM MST /10 AM PST/ Wednesday ABOVE
     5500 FEET for the Eastern Lemhi County...Southern
     Clearwater Mountains...Western Lemhi County.

     High Wind Warning until 10 AM PST Wednesday Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

     Wind Advisory until 10 AM PST Wednesday Northern Clearwater
     Mountains.

&&

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

7 high wind, 4 winter storm. Local standard time, as filed.

High Wind, Flathead/Mission Valleys

When: November 17, 5:00 PM MST to November 18, 5:00 AM MST
Where: Flathead/Mission Valleys forecast zone
Measured: 39 kt (45 mph) estimated sustained
Property damage: $25,000
Reported by: Trained Spotter
Coordinates: 47.872, -114.424 (the zone’s center; the record gives no point)

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.

Winter Storm, Bitterroot / Sapphire Mountains

When: November 17, 6:00 PM MST to November 18, 4:00 AM MST
Where: Bitterroot / Sapphire Mountains forecast zone
Reported by: Department of Highways
Coordinates: 46.508, -113.828 (the zone’s center; the record gives no point)

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.

High Wind, Lower Clark Fork Region

When: November 17, 6:00 PM MST to November 18, 2:00 AM MST
Where: Lower Clark Fork Region forecast zone
Measured: 39 kt (45 mph) estimated sustained
Property damage: $10,000
Reported by: RAWS
Coordinates: 47.286, -114.685 (the zone’s center; the record gives no point)

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.

High Wind, Missoula / Bitterroot Valleys

When: November 17, 8:00 PM MST to November 18, 5:00 AM MST
Where: Missoula / Bitterroot Valleys forecast zone
Measured: 51 kt (59 mph) measured gust
Property damage: $100,000
Reported by: ASOS
Coordinates: 46.560, -114.023 (the zone’s center; the record gives no point)

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, Missoula / Bitterroot Valleys

When: November 17, 8:00 PM MST to November 18, 5:00 AM MST
Where: Missoula / Bitterroot Valleys forecast zone
Measured: 57 kt (66 mph) measured gust
Reported by: AWSS
Coordinates: 46.560, -114.023 (the zone’s center; the record gives no point)

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.

Winter Storm, West Glacier Region

When: November 17, 8:00 PM MST to November 18, 8:00 AM MST
Where: West Glacier Region forecast zone
Property damage: $10,000
Reported by: Department of Highways
Coordinates: 47.971, -114.069 (the zone’s center; the record gives no point)

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, Potomac / Seeley Lake Region

When: November 17, 8:00 PM MST to November 18, 6:00 AM MST
Where: Potomac / Seeley Lake Region forecast zone
Reported by: RAWS
Coordinates: 46.986, -113.597 (the zone’s center; the record gives no point)

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, Kootenai/Cabinet Region

When: November 17, 9:00 PM MST to November 18, 3:00 AM MST
Where: Kootenai/Cabinet Region forecast zone
Measured: 57 kt (66 mph) measured gust
Reported by: RAWS
Coordinates: 48.171, -114.863 (the zone’s center; the record gives no point)

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, Kootenai/Cabinet Region

When: November 17, 9:00 PM MST to November 18, 3:00 AM MST
Where: Kootenai/Cabinet Region forecast zone
Measured: 52 kt (60 mph) estimated gust
Property damage: $60,000
Reported by: Emergency Manager
Coordinates: 48.171, -114.863 (the zone’s center; the record gives no point)

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, Butte / Blackfoot Region

When: November 17, 11:00 PM MST to November 18, 5:00 AM MST
Where: Butte / Blackfoot Region forecast zone
Measured: 52 kt (60 mph) measured gust
Property damage: $50,000
Reported by: Public
Coordinates: 46.306, -113.025 (the zone’s center; the record gives no point)

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, Butte / Blackfoot Region

When: November 18, 5:30 AM MST to 8:00 AM MST
Where: Butte / Blackfoot Region forecast zone
Reported by: Department of Highways
Coordinates: 46.306, -113.025 (the zone’s center; the record gives no point)

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.

What these are

High Wind: Sustained non-thunderstorm winds of 40 mph or more for an hour, or gusts of 58 mph or more.
Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Montana in 2015 Every state in 2015 This day in weather history Warnings in Montana, November 2015

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-30. Each event’s entry at NCEI: 609193, 607328, 609197, 607002, 607006, 607326, 607329, 605738, 605739, 607008, 607325.