The National Weather Service in Missoula is concerned about a major change in the weather for the holiday weekend.

Forecasters are calling for a snowier and colder pattern coming this weekend that could impact holiday travel on Sunday, especially over mountain passes.

“Our confidence is increasing when it comes to timing this event,” NWS said in a Nov. 26 press release. “However, snow amounts are still somewhat up in the air.”

For Northwest Montana, including north-central Idaho and Lookout and Lolo passes, NWS is forecasting light snow beginning Saturday, with an increase in snow showers overnight through Sunday morning over mountain pass roadways.

“Snow will really ramp up Sunday afternoon and become heavy through the day and through Monday, eventually becoming a valley road impact,” the forecasters said.

In addition to snowfall, some of the coldest air all season is expected to infiltrate Northwest Montana and north-central Idaho by Monday and Tuesday, with daytime highs in the single digits and teens and lows potentially going below zero.