Montana, 2021

Winter Storm in Montana, December 14, 2021

December 14, 2021 · NWS MSO · 1 event in 1 county or zone

A Pacific cold front brought heavy snow, gusty winds, and a quick drop in temperature across Southwest Montana.

Where it happened

Every event with a place to put it; 1 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
None recorded
Crop damage
None recorded
Events
1

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 Pacific cold front brought heavy snow, gusty winds, and a quick drop in temperature across Southwest 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 14, 4:21 AM MST, 9 hours 39 minutes earlier.

Area forecast discussion, Dec 14, 4:21 AM MST, 9 hours 39 minutes before
Area Forecast Discussion
National Weather Service Missoula MT
421 AM MST Tue Dec 14 2021

...Active Winter Weather pattern through the weekend...

.DISCUSSION...The Idaho County Sheriff posted on Facebook early
this morning that road conditions were poor on Highway 95 with
multiple slide-offs and stalled vehicles due to heavy snow. Snow
will persist this morning only to lessen in intensity by late
morning or early afternoon. In other locations in Montana and also
in Lemhi County, the precipitation has varied from rain, sleet to
snow. The rain in Kalispell will changeover to snow this morning.
A weather spotter call in from Libby to report that 3 inches of
snow has fallen since Monday afternoon. Mixed precipitation is
also possible across west-central Montana and a few locations will
also experience a changeover to snow once the more steady
precipitation shifts eastwards.

Some clearing is expected later tonight and will allow
temperatures across the region to fall into the teens and 20s most
valleys, but single digits in the mountains.

The next weather system arrives Wednesday night into Thursday
with the precipitation type mostly snow across north-central
Idaho and western Montana. The areas that will pick up the most
snow will be the Clearwater Mountains, 5 to 8 inches potentially
for the Elk River and Pierce areas, 3 to 6 inches for both
Lookout and Lolo Passes and Marias Pass. Lower Valleys could pick
up a dusting to 3 inches. Snow showers will persist through Friday
morning. An arctic airmass will shift southeast out of Alberta,
Canada Thursday night into Friday morning. Some of that colder air
could seep westward into the Glacier Park region. The main
impacts of that would be an enhanced potential for snowfall during
that timeframe with some south to east winds through Marias Pass
and Essex.

The 3rd weather system will impact the region Saturday and Sunday.
This trough will be a juicier than the last, so moderate to heavy
mountain snowfall is more likely. This could impact travel
through the mountain passes along the Idaho and Montana border.
There is a 50 percent chance that Lookout Pass could receive at
least 12 inches of snow during this event. Also another impact
will be strong south winds in the Camas Prairie on Saturday.

Looking further down the road into the following week... Latest
indications are that the large blocking high over the northern
Pacific with weather systems dropping southeastward out of Alaska will
continue. Slightly higher confidence is that an active pattern
will continue. This should continue to help the mountains build
snowpack. Lesser confidence with what will happen in the valleys,
maybe a continuance of a roller-coaster ride in terms of up and
down temperatures with varying precipitation types.

&&

.AVIATION...A weather system will bring mixed precipitation across
the region through 15/0300Z then partial clearing is expected.
Variable ceilings and visibility can be expected. SMN may
experience the best chance for snow later this afternoon, possibly
after 14/2000z. A brief break in the precipitation on Wednesday
before another snow-maker moves in by Thursday.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 5 PM MST this afternoon
     Butte/Blackfoot Region.

     Winter Weather Advisory until 11 AM MST this morning
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 11 AM MST this morning
     Missoula/Bitterroot Valleys.

     Winter Weather Advisory until 11 AM MST this morning Lower Clark
     Fork Region.

     Winter Weather Advisory until 11 AM MST this morning
     Flathead/Mission Valleys.

     Winter Weather Advisory until 11 AM MST this morning West
     Glacier Region.

     Winter Weather Advisory until 11 AM MST this morning
     Kootenai/Cabinet Region.

     Winter Weather Advisory until 11 AM MST this morning
     Potomac/Seeley Lake Region.

ID...Winter Weather Advisory until 11 AM MST this morning Eastern
     Lemhi County...Western Lemhi County.

     Winter Weather Advisory until 10 AM PST this morning Northern
     Clearwater Mountains...Southern Clearwater Mountains.

     Winter Weather Advisory until 10 AM PST this morning Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

&&

In the hours before

Local storm report, Dec 14, 8:02 AM MST, 5 hours 58 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
802 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0801 AM     SNOW             NINEMILE                47.02N 114.41W
12/14/2021  E5.0 INCH        MISSOULA           MT   PUBLIC

&&

RNL
Local storm report, Dec 14, 8:10 AM MST, 5 hours 50 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
810 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0809 AM     HEAVY SNOW       GRANGEVILLE             45.93N 116.12W
12/14/2021  M11.0 INCH       IDAHO              ID   PUBLIC

            SOCIAL MEDIA POST WITH A PICTURE OF A RULER
            STUCK IN THE SNOW.

&&

RNL
Local storm report, Dec 14, 8:46 AM MST, 5 hours 14 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
846 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0845 AM     SNOW             KOOSKIA                 46.15N 115.98W
12/14/2021  E2.0 INCH        IDAHO              ID   PUBLIC

            2 INCHES IN TOWN, ABOUT 4 INCHES ESTIMATED
            AT 2,400 FT OUTSIDE OF TOWN. FACEBOOK
            COMMENT.

&&

RNL
Local storm report, Dec 14, 8:53 AM MST, 5 hours 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
853 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0853 AM     SNOW             YAAK                    48.83N 115.71W
12/14/2021  M3.2 INCH        LINCOLN            MT   COCORAHS

&&

RNL
Local storm report, Dec 14, 9:22 AM MST, 4 hours 38 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
922 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0921 AM     HEAVY SNOW       GRANGEVILLE             45.93N 116.12W
12/14/2021  M11.8 INCH       IDAHO              ID   PUBLIC

            SECOND REPORT FROM GRANGEVILLE ON SOCIAL
            MEDIA WITH A PICTURE OF A RULER IN THE SNOW.

&&

RNL
Local storm report, Dec 14, 11:16 AM MST, 2 hours 44 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1116 AM MST TUE DEC 14 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1115 AM     HEAVY SNOW       1 ESE COTTONWOOD        46.05N 116.33W
12/14/2021  M8.0 INCH        IDAHO              ID   PUBLIC

            SOCIAL MEDIA POST WITH PICTURE OF RULER IN
            THE SNOW AT 8 INCHES.

&&

RNL

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 storm. Local standard time, as filed.

Winter Storm, Butte / Blackfoot Region

When
December 14, 2:00 PM MST to 8:30 PM 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)

Heavy snow, wind gusts to 30 mph, and falling temperatures led the Montana Department of Transportation to close I-90 over Homestake Pass between 424 pm and 550 pm. Two inches of snow was measured along the I-90 corridor from Deer Lodge to Butte during a 30 minute period as the front passed.

What these are

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

More

Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, December 2021

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: 997569.