Another plume of Pacific moisture and relatively milder air moved over the cold valleys of western Montana on December 1st. This brought wet snow to area mountain passes while freezing rain and drizzle made for slick driving conditions to a few valley locations.
Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
The episode as NWS MSO wrote it up.
Another plume of Pacific moisture and relatively milder air moved over the cold valleys of western Montana on December 1st. This brought wet snow to area mountain passes while freezing rain and drizzle made for slick driving conditions to a few valley locations.
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 30, 11:50 PM MST, 10 minutes earlier.
Area Forecast Discussion...UPDATED
National Weather Service Missoula MT
1150 PM MST Sat Nov 30 2013
.UPDATE...Upgrading the winter storm watch to a winter weather
advisory for the Flathead and Mission valleys. Freezing rain is
currently being reported across the Flathead valley and will
create slick travel conditions. Snow is expected in these
locations by Monday, making for a prolonged period of travel
difficulties.
&&
.AVIATION...Periodic snow/rain showers with pockets of freezing
rain will impact aviation across the Northern Rockies during the
next 24 hours. Valley fog and freezing fog will persist within
some valleys, while others will experience low stratus. Terrain
obscurations will be commonplace during this time. The snow/rain
showers will become much more numerous after 01/1800Z, marking the
beginning of a prolonged winter storm scenario over the region.
&&
.PREV DISCUSSION... /ISSUED 1118 PM MST Sat Nov 30 2013/
UPDATE...Upgraded the winter storm watch to a winter storm
warning for the Kootenai/Cabinet region in northwest Montana.
Freezing rain is currently being reported with ice forming on
roadways making for slick travel conditions. Snow will also come
into the picture tomorrow, especially for locations above 2500
feet. Travel conditions will continue to deteriorate through Monday.
.PREV DISCUSSION... /ISSUED 937 PM MST Sat Nov 30 2013/
UPDATE...Adding to the complexity of the upcoming weather
forecast, we have issued a Wind Advisory for the Grangeville area
and the Salmon River Drainage along Highway 95 starting Sunday
morning and continuing into Monday morning.
DISCUSSION...Conditions favor increasing south winds across much
of north-central Idaho and western Montana Sunday. However, the
Grangeville area and south along Highway 95 through the Salmon
River Drainage should some of the strongest winds with potential
gusts up to 55 mph later Sunday morning through early Monday
morning. Once the cold front passes through the area Monday
morning, winds will become more westerly and not quite as strong.
PREV DISCUSSION... /ISSUED 353 PM MST Sat Nov 30 2013/
HEAVY MOUNTAIN SNOW FOLLOWED BY ARCTIC AIR MONDAY NIGHT...
DISCUSSION...
Tonight a complex weather system really starts to impact the
region. Because this is such a complex storm system, we want to
highlight the biggest impacts that are expected:
1) HEAVY MOUNTAIN PASS AND BACK COUNTRY SNOWFALL: An atmospheric
river of tropical origins is currently making its way towards the
west coast and the Cascades. After causing heavy rain and flooding
there, the moisture plume will head eastward and impact the
northern Rockies. Areas of upslope flow in central Idaho and
western Montana will be hardest hit. This river will bring strong
winds and 200 percent of the normal amount of water to the western
slopes of the northern Rockies.
Mountain snow will be measured in feet with this system by the
time it is done, and Lolo, Lost Trail, and Lookout passes will be
have heavy snow tomorrow afternoon and evening. Those on
back country roads should be prepared for heavy snow so as to not
become trapped.
2) VALLEY RAIN CHANGING TO SNOW/CHANCE FOR MIXED PRECIP: While the
heavy snow is impacting the mountains, many of the valleys will be
warm enough for rain. Some isolated pockets of cold air may
persist in northwest Montana and cause very localized icy
conditions. Freezing rain Sunday morning is expected to be much
less than this morning. Throughout the night precipitation may
turn from rain to snow, and then possibly back to rain again
Monday morning.
Expect variable and rapidly changing conditions in the valleys of
northwest Montana, especially in the foothills surrounding the
valleys. Travel conditions will be difficult with the potential
for snow, slush, and ice through Monday morning.
3) ARCTIC FRONT: Timing is difficult as models still cannot agree
upon when the arctic front will arrive. The current consensus is
for northwest Montana to be impacted Monday late afternoon or late
evening and the front moves across western Montana and central
Idaho by late Tuesday morning. Confidence is high that the cold
air is coming, however timing remains uncertain.
There are several impacts that will make being outdoors or
traveling next week difficult and dangerous at times.
- Flash freezing of wet roads with the arrival of the cold air
- Low visibility and difficulty driving with blowing snow
- North winds 20-30 mph, especially through Hellgate and Bad Rock
canyons.
- Wind chills below -20 across northwest Montana Wednesday morning
- Coldest temperatures in 2 1/2 years from central ID through
western MT
The pattern will remain very cold through next weekend, with only
marginal chances of additional light snowfall. Overnight
temperatures will consistently be in the sub-zero and single digit
range for western Montana valleys, while central Idaho valleys
will be only slightly warmer. Daytime temperatures will remain
well below freezing. There is little sign of a pattern change
even after next weekend.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH from Sunday evening through late Tuesday
night Butte/Blackfoot Region...Missoula/Bitterroot Valleys.
WINTER STORM WARNING until 1 AM MST Wednesday
Bitterroot/Sapphire Mountains...Lower Clark Fork Region.
WINTER WEATHER ADVISORY until 1 AM MST Wednesday
Flathead/Mission Valleys.
WINTER STORM WARNING until 1 AM MST Wednesday Potomac/Seeley
Lake Region...West Glacier Region.
WINTER STORM WARNING until 1 AM MST Wednesday Kootenai/Cabinet
Region.
ID...WINTER STORM WATCH from Sunday evening through late Tuesday
night Eastern Lemhi County...Western Lemhi County.
WINTER STORM WARNING until Midnight PST Tuesday Night Northern
Clearwater Mountains...Southern Clearwater Mountains.
WIND ADVISORY from 10 AM Sunday to 7 AM PST Monday for the Camas
Prairie...Grangeville and Highway 95 IN THE Lower Hells
Canyon/Salmon River Region...Orofino/Grangeville Region.
&&
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https://www.facebook.com/US.NationalWeatherService.Missoula.gov
https://www.twitter.com/NWSMissoulaThe national radar mosaic for the moment the first event began.
5 winter weather, 1 heavy snow. Local standard time, as filed.
Freezing rain was reported in Troy and along Highway 37 during the morning hours making untreated road surfaces slick. SNOTEL stations in the mountains reported anywhere from 5 to 12 inches of wet snow.
SNOTEL sites in the Swan, Whitefish and Mission mountains reported 8 to 10 inches of snow with over an inch of liquid equivalent.
A person from Columbia Falls tweeted that roads were icy and treacherous due to freezing rain at 12 am MST. Montana DOT reported freezing rain on MT-40 from US-93 to the junction of US-2 and also on S-424 between Lodgepole Road to the junction with US-93.
The Superior 911 dispatch reported freezing rain that brought a glaze of ice to the nearby roads from 9 am to 1 pm MST. Montana DOT reported freezing rain on Interstate 90 between St. Regis to Tarkio during the morning. Snow fell at Lookout Pass during the morning hours with up to 4 inches of wet snow reported. Web-cams indicated that the pass had snow-covered and slick road during the morning. The Hoodoo Basin SNOTEL at 6,050 ft., located 14 miles west-southwest of Tarkio, reported 13 inches of total snow with 1.70 inches of snow water equivalent.
Rain fell during the early morning hours freezing to untreated secondary roads making for slippery travel in the Missoula and Bitterroot Valleys.
The Saddle Mountain SNOTEL at 7,900 ft., located about 1.7 miles west-southwest of Lost Trail Pass on US-93 received 15 inches of snow with 1.80 inches of snow water equivalent. An intense period of heavy snow occurred between 4 and 8 pm MST when 9 inches fell. At 1:40 pm MST, the Montana DOT reported that chains were required on towing units for Lost Trail Pass. During the morning hours, freezing rain was reported near Sula on US-93 causing very slick conditions. Several vehicles had slid off the road from Sula towards Lost Trail Pass.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2013Every state in 2013This day in weather historyWarnings in Montana, December 2013
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 2026-10-01. Each event’s entry at NCEI: 490135, 493209, 493210, 493211, 493593, 493212.