BOZEMAN – An active storm track with the next weather maker to produce widespread snow and much colder temperatures beginning Sunday night.
A slowly digging Low-pressure system will pass under Monana over the next 3 days. This will set up a persistent SW flow aloft and pave the way for ample moisture to pass through eastern Idaho, SW Montana, and western Wyoming.
A deep trough will also develop and open the door for colder Canadian air to sink southward. Temperatures will fall well below normal this week and could even fall down to zero or slightly below zero by Wednesday or Thursday.
The combination of widespread snow, localized gusty wind, much colder temperatures, wind chills below zero will bring our first severe winter storm to the region.
Be prepared for hazardous travel conditions and big impacts on morning and evening commutes beginning Monday morning. The worst travel conditions should be Monday afternoon through Tuesday morning. Additional snow is possible on Wednesday.
How much snow could we see? Latest forecast models have all valleys picking up snow with this event. The most likely outcome will be between 2”-6” of valley snow with a few lower valleys possibly picking up to 8” or more. Mountains and passes will see 6”-12” with the highest probability of heavy snow over the southern half of Beaverhead, Madison, Gallatin, and Park Counties and inside Yellowstone National Park.
Monida Pass over to Island Park, Raynolds Pass, Targhee Pass up to Big Sky will see periods of heavy snow with this storm system.
The National Weather Service issued a WINTER STORM WARNING on the Idaho side of Monida Pass over to Island Park, Idaho Sunday night through Tuesday evening. Inside Yellowstone National Park and up into the Absaroka-Beartooth range near Cooke City. 1 to 2 feet of snow is possible along with gusty winds, blowing snow, low visibility, and bitter cold wind chills.
The National Weather Service issued a WINTER STORM WARNING for the Ruby Mountains, Southern Beaverhead Mountains, Gallatin and Madison Ranges and the Centennial Range. General snow accumulations for these mountain ranges will be 8”-15” of snow, gusty winds, blowing snow, below zero wind chills.
The National Weather Service issued a WINTER WEATHER ADVISORY for SW Montana east of the divide Sunday night through Tuesday morning. Snow accumulations of 2"-6" is possible for lower valleys and mountains and passes. This storm will impact travel beginning Monday morning. Wind gusts to 35 mph are possible. This could produce areas of blowing snow and below zero wind chills.