Strong westerly flow moved across Central and Southwestern Montana on Saturday December 4th, which brought gusty winds across Southwestern Montana, along with some snow for the North-Central Plains.
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.
Strong westerly flow moved across Central and Southwestern Montana on Saturday December 4th, which brought gusty winds across Southwestern Montana, along with some snow for the North-Central Plains.
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 4, 12:05 PM MST, 1 hour 55 minutes earlier.
Area Forecast Discussion National Weather Service Great Falls MT 1205 PM MST Sat Dec 4 2021 ...Aviation Section Update... .UPDATE... Expanded the Winter Weather Advisory south from the Hi-Line to include more of north-central Montana based on observed trends with satellite, radar, and a model blend of the SREF and NBM, which seem to have the best handle on the best situation currently. Also issued a Winter Weather Advisory for the Southern Rocky Mountain Front and Central and Southern Lewis and Clark County zones for elevations above 5,000-ft elevation, where accumulations over the next 24 hours or so look to be significant enough to warrant such. Main concerns in those areas on the road system are Roger Pass and Flesher Pass, where close to 6 inches of snow accumulation are possible, mainly coming later today into tonight. If current trends continue with the 12z model runs, we will need to issue additional Winter Weather Advisories for the Little Belts for snow accumulations nearing 6 inches tonight, especially Kings Hill Pass. Stay tuned. There are no changes in thinking with the current High Wind Warning for southwest Montana. && .SYNOPSIS... Deep Pacific moisture in a westerly flow aloft will continue light accumulating snow over much of north central Montana today on the north side of a warm front. However, strong westerly winds will blow across much of southwest and central Montana, helping to keep temperatures between 10 and 20 degrees above normal. A disturbance with an associated cold front will then move a band of snow south through the region overnight, which will help cool temperatures to near and slightly below normal for Sunday. && .AVIATION... 1205 PM MST Sat Dec 4 2021 (04/18Z TAF period) A surface front moves northward through the area. Expect periods of rain and/or snow, with lowering ceilings. Conditions fall into the MVFR/IFR range, with KCTB experiencing observed LIFR conditions to start this TAF period. Mountain obscuration is forecast. Surface wind shifts are forecast with frontal passage. With a strong westerly flow aloft, low level wind shear conditions are included in all TAFs. Expect to encounter mountain wave. This evening, a second front presses southward into Montana from Canada, favoring deteriorating conditions in rain, becoming snow, and with lowering ceilings. Gusty winds continue across much of the area, through the night. - Fogleman Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 500 AM MST Sat Dec 4 2021/ Today through Sunday... The strong westerly flow aloft will drive the weather through the day today. Light snow has become widespread over north central and central Montana early this morning, as deep Pacific moisture overruns the colder airmass north of a warm front positioned over central Montana. Additional snow accumulations of 1 to 4 inches are likely on the plains of the Hi- Line today, with another 5 to 10 inches possible in the mountains of the Rocky Mountain Front, mainly above mountain pass level. Am therefore continuing the Winter Weather Advisories as is. As the warm front lifts northeast this morning, the light snow will decrease from the south and the strong winds aloft will start to mix down to the surface over southwest and central Montana, as 700 mb winds will increase to between 60 and 70 kt. Will therefore continue the High Wind Watch for this area as well. The warm front will continue to move to the Hi-Line late this afternoon into early this evening, which will help spread lesser westerly downsloping winds into this area, which will also help decrease the snowfall. Highs in the windier areas will warm to between 10 and 20 degrees above normal, but the Hi-Line will only warm to near normal. A shortwave trough in the flow aloft will then move slowly through Montana tonight into Sunday, which will shift the flow aloft more northwesterly. Moisture wrapping around this disturbance will combine with a Canadian cold frontal passage to bring another band of snow south through the forecast area overnight, with some light snow showers lingering in the mountains into Sunday. The strong winds aloft will keep the best chance for blowing snow in the mountains, but the passage of the cold front will shift winds more northwesterly over the plains, bringing a chance for blowing snow there as well tonight into Sunday. Temperatures through Sunday will remain up to 10 degrees below normal over north central Montana, as the southwest remains near normal. Monday through next Saturday... The flow aloft will remain northwesterly through the week as high pressure strengthens over the northeast Pacific Ocean. This will mostly keep temperatures cooler than normal with unsettled weather. The next good chance for snow will come with the passage of another shortwave trough with an associated Canadian cold front Monday into Monday night. With this being a fairly fast-moving system, snow accumulations are forecast to be somewhat light at this time. Temperatures will likely warm back above normal on Wednesday, which will likely keep any snow in the mountains with the passage of another disturbance. A broad low pressure trough will then move into the western and central United States to end the week, which will cool temperatures back below normal, but the chance for additional precipitation should remain in the mountains. -Coulston && .PRELIMINARY POINT TEMPS/POPS... GTF 48 17 25 9 / 60 50 20 0 CTB 38 13 21 3 / 100 50 10 0 HLN 54 24 33 17 / 30 70 20 0 BZN 55 27 38 16 / 10 60 20 10 WYS 39 24 32 14 / 10 50 30 20 DLN 54 27 38 19 / 0 20 0 0 HVR 33 10 23 -1 / 100 40 10 0 LWT 45 14 23 5 / 50 70 20 10 && .TFX WATCHES/WARNINGS/ADVISORIES... High Wind Warning until 11 PM MST this evening Beaverhead... Broadwater...Cascade...Central and Southern Lewis and Clark... Gallatin...Jefferson...Judith Basin...Madison...Meagher. Winter Weather Advisory until 11 AM MST Sunday Central and Southern Lewis and Clark...Southern Rocky Mountain Front. Winter Weather Advisory until 5 PM MST this afternoon Blaine... Eastern Glacier...Hill...Liberty...Toole. Winter Weather Advisory until 2 PM MST this afternoon Chouteau... Eastern Pondera...Eastern Teton...Fergus. Winter Weather Advisory until 5 AM MST Sunday Northern Rocky Mountain Front. && http://www.weather.gov/greatfalls
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1131 AM MST SAT DEC 4 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1128 AM SNOW 7 SSE ULM 47.33N 111.48W
12/04/2021 M1.3 INCH CASCADE MT TRAINED SPOTTER
ALSO MEASURED 0.10-INCH LIQUID WATER
EQUIVALENT.
&&
CCPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
1134 AM MST SAT DEC 4 2021
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1100 AM SNOW 5 WSW GREAT FALLS 47.46N 111.39W
12/04/2021 M1.4 INCH CASCADE MT OFFICIAL NWS OBS
&&
CC4 high wind. Local standard time, as filed.
Wise River mesonet station reports a wind gust of 60 mph. Other high wind reports were received in the area.
Bozeman Pass DOT sensor recorded a wind gust of 58 mph. Yellow Mule RAWS recorded a 57 mph wind gust around this time as well.
MT DOT sensor at Monarch Canyon reports a wind gust of 58 mph.
Elkhorn RAWS 8 miles west of Townsend reports wind gust of 66 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Montana in 2021Every state in 2021This day in weather historyWarnings in Montana, December 2021
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: 992454, 992457, 992455, 992453.