Up to a foot of snow could fall at Beartooth Pass beginning this evening, as a large system of colder, wetter weather is expected to bring rain and high-elevation snow through Saturday afternoon.
Temperatures have already begun dropping, and the National Weather Service is forecasting them to dip into the upper 30s in Billings and surrounding areas by Friday night. That's just three days after the mercury soared to 92 degrees on Tuesday, one degree short of tying the all-time record for Sept. 12.
"If anybody's hunting or anything, they should dress for cold weather up in the mountains," warned Brian Tesar, a meteorologist with the Weather Service's Billings office. "Most people aren't going to be acclimated to this type of cold weather all of a sudden."
Elevations above 7,000 feet can expect some amount of snow over the next two days, and Tesar added that even Red Lodge could see some flakes falling. The heaviest precipitation is forecast for Thursday night through Friday afternoon.
A winter storm warning goes into effect tonight for the Absaroka/Beartooth, Bighorn and Crazy mountains through Saturday at 6 p.m.
Closer to the Canadian border, the drought-stricken lands in the north-central and northeastern portion of Montana are likely to see less rain than areas to the south, the weather agency's Glasgow office stated in a press release Wednesday evening.
"A 50-mile shift in the upper-level low one way or another could be a drastic difference in the final rainfall totals," meteorologist Tanja Frasen stated in the release.
She also warned of possible flash-flooding where the July and Lodgepole fires charred vast swaths of range land earlier this summer.
"We have not seen flooding issues with past fires in 2003 or 2006, but they were not even half the size of this event," she noted, referring to the Lodgepole Complex that burned more than 270,000 acres in Petroleum and Garfield counties. "The best bet is to be cautious when traveling on gravel roads, especially west of the Snowy Divide into the Musselshell River along Calf and Lodgepole creeks."
In the Rock Creek drainage, she added that as little as a third of an inch of rain could create a flash-flood event.
Temperatures in Billings are expected to hover in the upper 30s to mid-50s through Saturday night. Mostly clear skies should return to the area by Sunday, along with high temperatures in the upper 60s to mid-70s during the first half of next week.