Winter Storm and Winter Weather in Montana, December 22 to 23, 2017

Name: Winter Storm and Winter Weather in Montana, December 22 to 23, 2017
Start: 2017-12-22T15:50
End: 2017-12-23T07:00
Location: Montana

December 22 to 23, 2017 · NWS MSO · 3 events in 3 counties and zones

An increase in snow during the evening commute led to numerous accidents across west-central Montana. A special alert for emergency travel only, was issued by Missoula County for Interstate 90 between Bonner to just east of Clinton for slick roads and blowing snow causing poor visibility and hazardous driving conditions.

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.

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 22, 2:29 PM MST, 1 hour 21 minutes earlier.

Area forecast discussion, Dec 22, 2:29 PM MST, 1 hour 21 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
229 PM MST Fri Dec 22 2017

...LIGHT SNOW AND SLICK CONDITIONS TO CONTINUE THROUGH TONIGHT IN
WRN MT...

...GRANGEVILLE, ID SNOW CONTINUES THROUGH TONIGHT...

.DISCUSSION...Light snow showers will continue this evening and
into tomorrow morning as the region is under northwest flow behind
the a recent cold front. East winds will continue around the
Hellgate and Badrock canyons until tomorrow morning. Winter
weather advisories remain out for these impacts in Western
Montana.

The biggest concern for safety remains travel. The cold air and
snow have combined to cause icy conditions on some area roads.
That will continue through this evening, and commuters this
evening should be prepared for a longer commute due to slick
conditions.

The Camas Prairie, Grangeville, and Whitebird hill will have more
snow tonight as the flow turns northerly this evening and upslope
flow enhances the snow fall in these areas. An additional 2 to 4
inches of snow is expected there.

Clearing skies Saturday night will lead into a cold start Sunday
morning with lows dropping below zero across much of the area. The
next widespread light to moderate snow event is set to begin
later Sunday afternoon lasting into Christmas Day. Valley snow
amounts of 2-4 inches (slightly higher across north-central Idaho)
with 6-9 inches for the mountains are expected, thus winter
driving conditions will continue to be a concern for those
traveling.

Next week will feature an active weather pattern, with below
normal temperatures and periodic bouts of snow, even in the
valleys. Forecast models vary considerably on the details and
timing but wintry weather is here to stay.

&&

.AVIATION...Low to mid clouds and snow showers will continue
through the evening. Conditions will improve tonight at KGPI,
while ceiling and visibility restrictions will continue to be an
issue at KBTM, KMSO, and KSMN through the night.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory until 5 AM MST Saturday
     Missoula/Bitterroot Valleys.

     Winter Weather Advisory until 11 PM MST this evening
     Flathead/Mission Valleys.

     Winter Weather Advisory until 11 PM MST this evening West
     Glacier Region.

     Winter Weather Advisory until 5 AM MST Saturday
     Bitterroot/Sapphire Mountains.

     Winter Weather Advisory until 5 AM MST Saturday Butte/Blackfoot
     Region...Potomac/Seeley Lake Region.

     Winter Weather Advisory until 11 PM MST this evening Lower Clark
     Fork Region.

ID...Winter Weather Advisory until 8 AM PST Saturday Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

     Winter Weather Advisory until 4 AM PST Saturday Northern
     Clearwater Mountains...Southern Clearwater Mountains.

&&

In the hours before

Local storm report, Dec 22, 11:15 AM MST, 4 hours 35 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
1115 AM MST FRI DEC 22 2017

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

1115 AM     SNOW             2 WSW COLUMBIA FALLS    48.37N 114.21W
12/22/2017  M7.0 INCH        FLATHEAD           MT   TRAINED SPOTTER

&&

Local storm report, Dec 22, 3:29 PM MST, 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
329 PM MST FRI DEC 22 2017

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

0230 PM     SNOW             4 NNE LOLO              46.81N 114.05W
12/22/2017  M5.0 INCH        MISSOULA           MT   NWS EMPLOYEE

&&

The radar

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

Open the radar archive at this moment

Event by event

2 winter storm, 1 winter weather. Local standard time, as filed.

Winter Storm, Missoula / Bitterroot Valleys

When: December 22, 3:50 PM MST to December 23, 4:00 AM MST
Where: Missoula / Bitterroot Valleys forecast zone
Reported by: County Official
Coordinates: 46.560, -114.023 (the zone’s center; the record gives no point)

Due to an increase in snow intensities during the evening commute, Missoula county officials issued an emergency travel only alert from Bonner east to the Missoula/Granite county line along Interstate 90. NWS employees reported 5 inches of snow near South Hills and 7 inches in Lolo. Numerous accidents were observed between Missoula and Clinton and between Missoula and Lolo.

Winter Storm, Potomac / Seeley Lake Region

When: December 22, 3:50 PM MST to December 23, 2:00 AM MST
Where: Potomac / Seeley Lake Region forecast zone
Reported by: County Official
Coordinates: 46.986, -113.597 (the zone’s center; the record gives no point)

A Missoula county official issued a MEANS alert for emergency travel only for I-90 between Bonner and the Missoula/Granite county line due to slick roads and blowing snow creating poor visibility and hazardous driving conditions. Numerous slide offs were observed on I-90 on the incident report.

Winter Weather, Butte / Blackfoot Region

When: December 22, 3:50 PM MST to December 23, 7:00 AM MST
Where: Butte / Blackfoot Region forecast zone
Reported by: Trained Spotter
Coordinates: 46.306, -113.025 (the zone’s center; the record gives no point)

A trained spotter in Anaconda reported 7 inches of snow with this winter storm. Road reports from Montana Department of Transportation reported blowing and drifting snow across portions of I-90 in southwest Montana.

What these are

Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.
Winter Weather: Snow, sleet or freezing rain below warning levels that still caused disruption, damage or casualties.

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

The same day elsewhere

Every storm in Montana in 2017 Every state in 2017 This day in weather history Warnings in Montana, December 2017

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: 726651, 726662, 727209.