An arctic air mass settled over Choteau and north-central Montana on Monday, and the National Weather Service advised that it would likely persist until the end of the week before temperatures started moderating.
“This will bring the coldest temperatures of this winter season so far. Many locations will see daytime temperatures in the single digits above and below zero, with overnight temperatures of 20-below to 30-below zero. Wind chills may approach the 20-below to 40-below zero degree range,” the NWS advised on its website, https://www.weather.gov/tfx/.
“If you have to be outdoors this week, remember to wear layers (including a hat and gloves) to stay safe from the dangers of frostbite and hypothermia.”
As of Monday, January’s weather will be quite different than the mild conditions in December, now that arctic air has arrived. On Monday the temperature at the Choteau airport dipped to -14.8 for an hour at 7 a.m. and was expected to be lower by Monday evening. The high on Saturday was 42 degrees but it steadily got colder. At 3 a.m. on Sunday the temperature dropped from 28 to 12 in 15 minutes and it continued downward as of presstime.
The official low on Sunday in Choteau was -2 where 13 above is normal for Jan. 12. As of that date, the city’s average temperature for January was four degrees above the normal 24.9, but that was before the cold front arrived.
Another .4 inch of new snow fell on Jan. 9-10, bringing the snow year’s total to a record 70.3 inches as of Jan. 12. That’s more snow than fell during the whole 2018-19 snow year that began on July 1, 2018, and ended on June 30, 2019. The normal snowfall by Jan. 12 is 15.2 inches.
“Mountain snowpack east of the Divide received an early boost in September and October and now ranges from below normal in southwest Montana to above normal as you move north along the Divide,” reported Lucas Zukiewicz, USDA Natural Resources Conservation Service water supply specialist for Montana on Jan. 8. He provided a summary of December weather, noting that the large-scale weather patterns over western Montana remained the same throughout most of December, but unlike the previous month, December resulted in a lack of precipitation statewide.
According to Zukiewicz, the last 10 days of December featured an “atmospheric river” pointed squarely at the northwest corner of the state that provided abundant moisture at the SNOTEL sites along the Canadian border in northwest Montana and interior British Columbia. The weather patterns through the end of the month remained active, dropping significant amounts of snowfall at mountain locations across western Montana.
The Sun, Marias and Teton basins’ snow water equivalent, as of Jan. 12, measured 124 percent of normal, but 93 percent of normal for the water-year-to-date that began on Oct. 1, according to the NRCS Montana SNOWTEL snow/precip update report.
Mount Lockhart at 6,400 feet has 11.8 inches SWE, or 119 percent, the Waldron Creek station at 5,600 feet, has 6.4 inches SWE at 121 percent. The snow water equivalent represents the depth of water in the snowpack if the snowpack was melted expressed in inches.
The NWS noted an “extreme” cold advisory for newborn livestock based on the next few days. Extreme means a wind chill of -18 or colder for two or more hours, or wind chill less than 32 degrees and .1 inch of precipitation.
January 1950 was Choteau’s coldest January, with an average temperature of -6.6. The temperature got down to -41 during the first week. “Water out of a boiler resulted in no school at Choteau High School in the afternoon,” the Acantha reported, adding that it was fixed the next day.
On Jan 26, 1950, the Acantha reported, “Biting winds with 30-below temperatures brought a ragged appearance to cattle by Tuesday of this week, cattlemen reported. Many ranchers have been forced to hibernate because of the roads and dangerously low temperatures. A number of country schools have been closed for several days because of travel conditions, although most main highways have been open to travel.”
The report continued, “Last weekend a brief respite from the monotonous cold was experienced when a Chinook wind melted snows for two days. But then another cold wave sent thermometers down to the level where the mercury has been during most of the month.”
The only cattle reported lost that month were on the Charles Baker place east of Farmington when sparks thrown by a tractor as men were grinding hay started a barn fire. “Fire quickly razed the barn, killed two calves in the structure and burned feed, barley, oats, harness and other equipment.”
“Hay on the west side of the barn turned into a ball of fire in a matter of seconds,” Baker said. Firemen from Sheriff Al Peterson’s Teton County rural firefighting unit at Choteau and neighbors salvaged grain, feed and stopped the blaze from spreading to other buildings. Mr. and Mrs. Baker said the assistance was of great help in preventing further loss.