Winter Storm and Heavy Snow in Montana, December 11 to 12, 2016

Name: Winter Storm and Heavy Snow in Montana, December 11 to 12, 2016
Start: 2016-12-11T15:00
End: 2016-12-12T20:00
Location: Montana

December 11 to 12, 2016 · NWS MSO · 3 events in 3 counties and zones

Moist westerly flow brings Pacific moisture over cold air in place producing moderate to heavy snow over portions of west-central Montana.

Where it happened

Every event with a place to put it; 3 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

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 3

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.

Moist westerly flow brings Pacific moisture over cold air in place producing moderate to heavy snow over portions of west-central Montana.

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 Dec 11, 3:28 AM MST, 11 hours 32 minutes earlier.

Area forecast discussion, Dec 11, 3:28 AM MST, 11 hours 32 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
328 AM MST Sun Dec 11 2016

...ARCTIC FRONT EXPECTED TO BRING ADDITIONAL SNOW, BLOWING &
DRIFTING SNOW, AND BLUSTERY WIND CHILLS BY MONDAY...

.DISCUSSION...
A steady stream of light to moderate snowfall continues for
north-central Idaho and western Montana this morning. Accumulating
snow amounts have not been as significant as the previous event
so far, but locations along the Idaho/Montana border such as Lolo
Pass and Lookout Pass could see significant snow amounts now
through this evening. Increasing instability this
morning/afternoon may also lead to heavier convective snow showers
that would bring locally heavier snow amounts, especially for
northwest Montana and north-central Idaho. Thus, winter weather
advisories remain in effect today for areas receiving additional
accumulating snowfall on top of precedent snowy/icy roadways.

Late tonight into Monday morning, a Canadian arctic airmass will
make its way over the Continental Divide and into northwest
Montana. This front will introduce strong gusty winds and blustery
wind chills such as through Bad Rock Canyon and along the Divide.
Snowfall will continue to be enhanced along this cold air
boundary, particularly in northwest/west-central Montana and
portions of north-central Idaho. These elements combined will
result in treacherous winter driving conditions and areas of
blowing/drifting snow with reduced visibilities. The arctic front
will track southward throughout Monday, and the colder
temperatures will make for challenging snow/ice mitigation efforts
on area roadways.

The snow and wind will taper off Tuesday, but the cold air mass
will remain in place supporting very cold overnight temperatures
by Tuesday night. Locations along the Divide could see significant
sub-zero temperatures during this period.

Another round of very moist air will track northeastward on
Thursday/Friday in front of another very cold air mass. Although
forecast details remain unclear at this time, bitterly cold
temperatures and additional accumulating snowfall are likely to
continue for the Northern Rockies.

&&

.AVIATION...
Light to moderate widespread snow showers will continue for north
central Idaho, the MT/ID border, and much of western Montana
today. KMSO, KGPI, and KSMN are most affected by this moisture
today. Precipitation will keep cloud ceilings low and promote
mountain obscurations and reduced visibilities. Snowfall
intensities may increase later this morning/this afternoon as
instability increases across the area.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 11 PM MST this evening
     Bitterroot/Sapphire Mountains...Lower Clark Fork Region.

     Winter Storm Watch from late tonight through Monday evening
     Missoula/Bitterroot Valleys...Potomac/Seeley Lake Region.

     Winter Storm Watch from this evening through Monday evening
     Flathead/Mission Valleys...West Glacier Region.

ID...Winter Weather Advisory until 10 PM PST this evening Northern
     Clearwater Mountains...Southern 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

1 winter weather, 1 heavy snow, 1 winter storm. Local standard time, as filed.

Winter Weather, Potomac / Seeley Lake Region

When: December 11, 3:00 PM MST to December 12, 8:00 PM MST
Where: Potomac / Seeley Lake Region forecast zone
Reported by: Trained Spotter
Coordinates: 46.986, -113.597 (the zone’s center; the record gives no point)

A trained spotter from Condon reported 7 inches of snow while a COOP observer from Lindbergh Lake recorded a storm total of 11.3 inches of snow with 0.87 inches snow water equivalent. Other areas along Highway 200 and Interstate 90 saw anywhere from 1 to 3 inches of snow that brought slick and snow-packed roads.

Heavy Snow, Lower Clark Fork Region

When: December 11, 5:00 PM MST to December 12, 1:30 PM MST
Where: Lower Clark Fork Region forecast zone
Reported by: Department of Highways
Coordinates: 47.286, -114.685 (the zone’s center; the record gives no point)

Lookout Pass had reported 21 inches of snow in 20 hours ending noon on Dec. 12th. Over a foot of snow was estimated towards Haugan. A person from the Montana Department of Transportation reported that it was an extremely busy weekend with almost non-stop snowfall.

Winter Storm, West Glacier Region

When: December 11, 5:00 PM MST to December 12, 8:00 AM MST
Where: West Glacier Region forecast zone
Reported by: Mesonet
Coordinates: 47.971, -114.069 (the zone’s center; the record gives no point)

Anywhere from 9 inches of snow by Marias Pass to 13.5 inches at West Glacier fell with this storm. An Arctic cold front plowed through Marias Pass which caused temperatures to drop from the middle 20's to single digits below zero in a matter of two hours. Combined with winds gusting near 30 mph, the wind chills ranged between -20 and -30 degrees. Blowing snow was reported by MDT during the night along US 2. The Arctic cold front lost steam as it made its way toward Columbia Falls and the Flathead Valley where only 2 to 3 inches of snow fell.

What these are

Winter Weather: Snow, sleet or freezing rain below warning levels that still caused disruption, damage or casualties.
Heavy Snow: Snowfall reaching the local warning threshold without the other hazards of a winter storm.
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 2016 Every state in 2016 This day in weather history Warnings in Montana, December 2016

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 2026-09-24. Each event’s entry at NCEI: 667196, 667134, 667239.