Arctic air dropped south from Canada the week before Christmas bringing widespread frigid wind chills to the region. The arctic front reported in strong wind gusts and blizzard conditions in Southwest Montana.
Every event with a place to put it; 39 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 TFX wrote it up.
Arctic air dropped south from Canada the week before Christmas bringing widespread frigid wind chills to the region. The arctic front reported in strong wind gusts and blizzard conditions in Southwest Montana. Additional areas of light to moderate snow affected much of the region.
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 Great Falls, MT wrote its last area forecast discussion before the first event at Dec 18, 10:50 PM MST, 1 hour 10 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1050 PM MST Sun Dec 18 2022 Aviation Section Updated .SYNOPSIS... Arctic air will remain entrenched over the Northern rockies for much of the week, with Wednesday and Thursday likely being the coldest days of the week. Additionally, periods of snow are expected through Wednesday. The Arctic air begins to retreat on Friday, with temperatures trending closer to average for most locations by Christmas Day. && .UPDATE... Several southwest valley locations are already several degrees below the lowest statistical guidance, so lowered temperatures to a blend of the NBM 10th and 25th percentiles of the probabilistic range in this area. High temperatures over much of the region were lower than forecast, so I continued that trend into Monday, also blending downward to the NBM 25th percentile. No other significant changes to note. Winter weather hazard statements have been updated as well. && .AVIATION... 1050 PM MST Sun Dec 18 2022 (19/06Z TAF period) The most impacts will occur over Central/North Central MT this period, with very light snow/flurries continuing, along with low ceilings. The snow will diminish a bit after 16z Mon. Generally MVFR/VFR conditions expected over Southwest MT. Mountains/passes will be obscured in the north through the period...a bit less mountain obscuration over Southwest MT. Brusda Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information && .PREV DISCUSSION... /ISSUED 450 PM MST Sun Dec 18 2022/ Today through Monday...A bitterly cold air mass will remain over the Northern Rockies for much of this week, though there will be periods of slightly milder temperatures over the southwest. A pressure gradient over the southwest is weakening for some reduction in wind speeds, though breezy to at times windy conditions will continue. The blowing/drifting snow situation in the Monida Pass area has improved, so the Winter Weather Advisory was allowed to expire at 11 am MST. Areas of light snow continue over the plains as milder westerly flow aloft overruns the arctic air mass. A more organized area of snowfall is occurring along and west of the northern Continental Divide, which is associated with an approaching broad and cold trough of low pressure. This system will move across the region tonight, bringing a brief period of more organized snow to central/north-central MT and will reinforce the colder air in place. The Winter Weather Advisory over the East Glacier area was expanded to include the Southern Rocky Mountain Front (public zone 307). Otherwise, no lower elevation winter weather products are being sent out for this due to the short duration of the event, but Special Weather Statements may be needed to address the short term impacts. No changes were made to the wind chill products through Monday afternoon. Temperatures for this period were adjusted lower towards the NBM 25th percentile and the GFS. Monday night through Wednesday...The cold air really intensifies in the wake of the passing shortwave trough, with lows falling into the 20 to 30 below range over the plains and possibly down to 10 to 15 below for portions of the southwest. Daytime highs on Tuesday will not be much better, with afternoon readings struggling to reach 10 below for some areas. There is a little more uncertainty on how cold southwest locations will stay. For now I trended closer to the colder GFS, which keeps above zero readings confined to areas south of I-90. Another shortwave moves in Tuesday into Wednesday, bringing accumulating snow followed by another intense blast of Arctic air. Given the strong frontogenesis, dynamics, and cold nature of this system, I decided to go with a Winter Storm Watch Tuesday afternoon through Wednesday afternoon for locations along the Rocky Mountain Front and portions of Central/Southwest MT. There is some uncertainty on how far north the accumulating snow will get, but areas extending from Helena to the Bozeman area could see the heaviest snow along with gusty winds and blowing snow. Bitter cold temperatures on Wednesday will be in the teens below zero in the north and will fall below zero over the southwest during the day. An anomalously strong high pressure system is poised to pass through Central/North-central MT Wednesday night, potentially threatening daily/monthly record low temperatures. Of course, lingering cloud cover and nocturnal breeziness can work against the coldest temperatures being realized. The core of the cold air remains entrenched over the region during the day on Thursday as highs remain well below zero for the entire region. Regardless of specific values, this is a dangerously cold air mass, with life threatening impacts to anyone outdoors, especially for individuals not prepared or properly dressed for the barbaric conditions. The Wind Chill Watches were upgraded to Wind Chill Warnings and the start time was moved up to Monday evening for central/north-central locations and Wednesday afternoon for the remainder of the region. -RCG Thursday night into Christmas Day...Another very cold night is expected Thursday night, though temperatures may begin to moderate toward the morning hours as a stronger and warmer westerly flow begins to erode the Arctic air. The very cold air will start to move east on Friday, as an upper level ridge tries to build over the Pacific Northwest, resulting in a northwesterly flow aloft over Montana. Note, the cold air will likely take an extra couple of days to move out of the Havre/Harlem areas. The Wind chill Warnings were extended through Thursday evening in the southwest and Friday morning farther north. Additional Wind Chill Advisories may be needed for portions of north-central MT on Friday. Blowing snow could become impactful on the eastern aspects of higher terrain along the Rocky Mountain Front and the plains as westerly winds increase Friday into the weekend. Also, as the warmer air moves in, some precipitation is possible. a few forecast soundings show warmer air moving in aloft faster, so there is some potential that we could have some freezing rain issues on Friday. The chances for precipitation decrease over the weekend, as temperatures slowly rebound closer to seasonal normals. -Brusda/RCG && .PRELIMINARY POINT TEMPS/POPS... GTF -15 -10 -24 -11 / 70 60 10 40 CTB -20 -12 -31 -14 / 80 20 10 30 HLN -17 -2 -15 -7 / 50 60 10 30 BZN -14 8 -11 4 / 10 10 10 30 WYS -10 13 -2 19 / 30 50 30 60 DLN -5 12 2 21 / 0 10 0 20 HVR -16 -9 -33 -13 / 80 60 10 40 LWT -16 -9 -21 -9 / 20 50 20 50 && .TFX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until noon MST Monday for East Glacier Park Region-Southern Rocky Mountain Front. Wind Chill Advisory until 6 PM MST Monday for Bears Paw Mountains and Southern Blaine-Cascade County below 5000ft-East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Fergus County below 4500ft-Gates of the Mountains-Hill County-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Northern Blaine County-Northern High Plains- Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front-Western and Central Chouteau County. Wind Chill Warning from 6 PM Monday to 11 AM MST Friday for Bears Paw Mountains and Southern Blaine-Cascade County below 5000ft-East Glacier Park Region-Eastern Glacier, Western Toole, and Central Pondera-Eastern Pondera and Eastern Teton-Eastern Toole and Liberty-Fergus County below 4500ft-Gates of the Mountains-Hill County-Judith Basin County and Judith Gap-Little Belt and Highwood Mountains-Northern Blaine County-Northern High Plains-Snowy and Judith Mountains-Southern High Plains-Southern Rocky Mountain Front-Western and Central Chouteau County. Winter Storm Watch from Tuesday afternoon through Wednesday afternoon for Beaverhead and Western Madison below 6000ft-Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-East Glacier Park Region-Elkhorn and Boulder Mountains-Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains-Gates of the Mountains-Helena Valley-Madison River Valley-Meagher County Valleys-Missouri Headwaters-Northwest Beaverhead County-Southern Rocky Mountain Front-Upper Blackfoot and MacDonald Pass. Wind Chill Warning from noon Wednesday to 6 PM MST Thursday for Beaverhead and Western Madison below 6000ft-Big Belt, Bridger and Castle Mountains-Canyon Ferry Area-Elkhorn and Boulder Mountains-Gallatin Valley-Gallatin and Madison County Mountains and Centennial Mountains-Helena Valley-Madison River Valley- Meagher County Valleys-Missouri Headwaters-Northwest Beaverhead County-Ruby Mountains and Southern Beaverhead Mountains-Upper Blackfoot and MacDonald Pass. && http://www.weather.gov/greatfalls
The national radar mosaic for the moment the first event began.
30 extreme cold/wind chill, 3 heavy snow, 2 winter storm, 2 blizzard, 2 high wind. Local standard time, as filed.
Badger Pass SNOTEL reported 9 inches of snow over a 24 hour period, most falling during the day on Tuesday, December 20th.
Multiple sensors measured wind chills of less than -40 F, including the Big Flat / Turner Agrimet (BFTM) which measured a minimum wind chill of -59 F.
Multiple sensors measured wind chills of less than -40 F, including coop station 6W0659 2 miles southeast of Grassy Butte which measured a minimum wind chill of -61 F.
Multiple sensors measured wind chills of less than -40 F, including the Browning DOT sensor (MTBWG) which measured a minimum wind chill of -54 F.
Multiple sensors measured wind chills of less than -40 F, including coop station DW0217 in northeastern Hill county which measured a minimum wind chill of -66 F.
Multiple sensors measured wind chills of less than -40 F, including the Sunburst DOT sensor (MTSUN) which measured a minimum wind chill of -61 F.
Multiple sensors measured wind chills of less than -40 F, including the Fort Belknap RAWS (FBLM8) which measured a minimum wind chill of -58 F.
Multiple sensors measured wind chills of less than -40 F, including mesonet station FW8526 Big Sandy which measured a minimum wind chill of -59 F.
Multiple sensors measured wind chills of less than -40 F, including the DOT sensor in Pendroy (MTPND) which measured a minimum wind chill of -58 F.
Multiple sensors measured wind chills of less than -40 F, including mesonet station COAM8 Conrad which measured a minimum wind chill of -55 F.
Multiple sensors measured wind chills of less than -40 F, including Deep Creek RAWS (DCRM8) which measured a minimum wind chill of -48F.
Multiple sensors measured wind chills of less than -40 F, including AWOS station K1OM Oscar which measured a minimum wind chill of -58 F.
Multiple sensors measured wind chills of less than -40 F, including the DOT sensor at Geyser (MTGYS) which measured a minimum wind chill of -58 F.
Multiple sensors measured wind chills of less than -40 F, including the DOT sensor on MacDonald Pass (MTMDP) which measured a minimum wind chill of -59 F.
Multiple sensors measured wind chills of less than -40 F, including the DOT sensor near Sieben (MTSBN) which measured a minimum wind chill of -52 F.
Spotter reported 6 inches of new snow over a 10 hour period.
Frohner Meadow SNOTEL site reported 6 inches of new snow over an 8-hour period.
One location measured a wind chill of -40 F or less, which was the Benchmark RAWS (BEFM8) which measured a minimum wind chill of -41 F.
Multiple sensors measured wind chills of less than -40 F, including the DOT sensor near Monarch (MTMON) which measured a minimum wind chill of -57 F.
Multiple sensors measured wind chills of less than -40 F, including mesonet station FW7359 in Helena which measured a minimum wind chill of -44 F.
Multiple sensors measured wind chills of less than -40 F, including the Little Snowy RAWS (LSNM8) which measured a minimum wind chill of -47 F.
Very strong winds occurred during a winter storm. The Wise River Raws (WRSM8) measured a 60 mph gust. Several additional sites across nearby areas gusted around 50mph at times during the event.
Multiple sensors measured wind chills of less than -40 F, including the Great Falls ASOS (KGTF) which measured a minimum wind chill of -57 F.
Mesonet station GNFHY Avalanche measured a 58 mph wind gust. While snowfall amounts were generally low, very strong wind resulted in significant blowing and drifting of snow across area mountain roads and passes.
The Dillon ASOS (KDLN), and a utility company reported blizzard conditions over a few hour period behind an arctic front.
The Brenner Raws (BRRM8) measured a gust of 59 mph.
Multiple sensors measured wind chills of less than -40 F, including DOT sensor Norris Hill (MTNOR) which measured a minimum wind chill of -57 F.
Multiple sensors measured wind chills of less than -40 F, including DOT sensor Deep Creek Pass (MTDPC) which measured a minimum wind chill of -48 F.
Multiple sensors measured wind chills of less than -40 F, including the Ginger RAWS (GINM8) Which measured a minimum wind chill of -51F.
AWOS station krvf Ruby Valley Field measured a 67 mph gust before power was lost at the station.
Mesonet site MTM56 approximately five miles southwest of Twin Bridges reported near blizzard conditions through much of the morning.
Multiple sensors measured wind chills of less than -40 F, including a DOT sensor on Boulder Hill (MTBOU) which measures a minimum wind chill of -58 F.
Multiple sensors measured wind chills of less than -40 F, including ASOS station KBZN which measured a minimum wind chill of -53 F. KBZN ASOS also had a peak minimum air temperature of -45 F the morning of December 22nd, which was one degree shy of tying the all time record low for the airport. The high temperature for December 22nd at KBZN was only -24 F. Approximately 75 reports of broken water pipes were noted across the Gallatin Valley area due to the extreme cold.
Multiple sensors measured wind chills of less than -40 F, including mesonet station 1653 D near Logan which measured a minimum wind chill of -49 F.
Multiple sensors measured wind chills of less than -40 F, including Agrimet station WSSM in White Sulphur Springs which measured a minimum wind chill of -54 F.
Multiple sensors measured wind chills of less than -40 F, including the Dillon ASOS (KDLN) which measured a minimum wind chill of -49 F.
Multiple sensors measured wind chills of less than -40 F, including mesonet station MTM17 BLM - Virginia City which measured a minimum wind chill of -57 F.
Multiple sensors measured wind chills of less than -40 F, including the Antelope RAWS (LMRM8) which measured a minimum wind chill of -58 F.
Only one station measured a wind chill less than -40 F which was the Wise River RAWS (WRSM8) Which measured a minimum wind chill of -46 F.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2022Every state in 2022This day in weather historyWarnings in Montana, December 2022
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: 1073261, 1070164, 1070159, 1070161, 1070163, 1070162, 1070165, 1070169, 1070167, 1070168, 1070160, 1070170, 1070172, 1070176, 1070175, 1073293, 1073295, 1070166, 1070174, 1070178, 1070171, 1073562, 1070173, 1073561, 1070194, 1070190, 1070185, 1070180, 1070179, 1070192, 1073244, 1070189, 1070183, 1070182, 1070181, 1070188, 1070184, 1070187, 1070186.