West of the Continental Divide:

Below: Light snow has already started at Whitefish at noon on Thursday. 

 
The impressive high-pressure ridge over the west coast is directing copious amounts of Pacific moisture in a line from the Hawaiian Islands all the way into the Gulf of Alaska. An Alaskan shortwave low-pressure system is tapping into this river of moisture as it rides southward through BC and Alberta arriving in the Northern Rockies around mid-afternoon on Thursday. The storm system will spread snow, sometimes heavy across the entire region Thursday night through Friday morning. 

Latest model runs show the brunt of the moisture falling essentially along the I-90 corridor across West Central Montana where Montana Snowbowl looks perfectly positioned to see close to 2 feet by last chair on Friday, and that’s not even the end of the snowstorm. Lookout Pass and Discovery also looks good for 6 to 12”, with Lost Trail Pass, Blacktail Mountain and Whitefish Mountain falling in the 3 to  7” range through 4PM Friday. Temps will stay seasonal for one more day on Friday with light and variable west winds 

As the North/NW flow brings a second low-pressure circulation into the region it appears to strengthen along the arctic airmass boundary sitting just east of the Continental Divide Friday night. This low will help draw the frigid arctic air over the Divide while also providing additional lift for Pacific moisture to add another several inches Friday night into Saturday morning. Snowbowl and Discovery are best positioned to see another heavy snow event adding another 7 to 11” into Saturday morning. Elsewhere, Whitefish will be riding just north of the main moisture wrap adding another 2 to 4”, with Lookout, Lost Trail, and Blacktail looking at an additional 3 to 5”. 

Gusty east to NE winds will really kick up as the arctic air spreads through the region on Saturday. Surface temps at 6000’ at Whitefish are expected to plummet to 4F by noon on Saturday. Disco and Snowbowl will see upper-mountain high temps of around 6F on Saturday, with Lost Trail and Lookout around 10F. The storm system will slowly clear out on Saturday as the arctic airmass spreads, essentially drying things out as high-pressure begins to build in. Sunday morning will see some frigid temps as clearing overnight drops temps to around -10F for most locations. Sunday, a mix of sun and clouds with temps not moderating all that much. Highs will range from around 0F at Whitefish to the warm spot of 5F at Lookout Pass.      
 
 East of the Continental Divide:

Below: The snow plot at Big Sky on Thursday afternoon. I bet it will be completely buried by Saturday.

The snow has been falling at Showdown and Big Sky overnight, both picking up a fresh 2 to 4” by first chair Thursday. The wind as also been a factor as Bridger Bowl has several lifts on wind hold Thursday. Look for light snow to continue for most locations Thursday along with moderate to strong W/NW winds with light accumulations of a trace to 2” across the region

Winter Storm Warnings and Advisories blanket the region for heavy snowfall through Saturday night. The action gets going Thursday evening as a moisture packed shortwave low-pressure circulation moving in on a northerly flow from Canada will begin to bring periods of heavy snow across the Northern Rockies. SW Montana locations Big Sky and Bridger Bowl look best positioned for 5 to 10” overnight, with around 3 to 5” at Showdown, with 1 to 2” possible at GD, Red Lodge, Teton Pass and Maverick. Temps stay at seasonal norms overnight and through most of the day on Friday. 

As the shortwave continues to bring periods of light snow through the morning hours on Friday, an arctic cold front will undercut the Pacific moisture Friday afternoon resulting in widespread heavy snowfall that looks to last into Friday night. Daytime accumulations of an additional 6 to 10” at Big Sky and Bridger, with 3 – 6” at Showdown, and 2 to 4” elsewhere across the eastside of the Divide. Moderate and gusty NW winds to 35 mph possible across the region with the passing cold front.  

As additional frigid Canadian air rides under the Pacific moisture stream Friday night, look for periods of snow to continue through the morning hours on Saturday. This will likely add overnight snow totals of 4 to 8” at Big Sky, Bridger Bowl, and Great Divide, with slightly lesser amounts of 2 to 4” at Showdown, Maverick, and Teton Pass. Red Lodge will see the brunt of the storm hit them Friday night with 6 – 10” possible overnight. Partial clearing across the region through the afternoon on Saturday as arctic high-pressure begins to build with decreasing N/NW winds. Temps will be brutally cold on Saturday with upper mountain highs around zero at Red Lodge, Showdown, Teton Pass, and Great Divide, with 5F above at 8000’ at Big Sky and Bridger. Light north winds Saturday. 

Arctic air will keep snow showers in the forecast Saturday night adding trace amounts up to 2” for most locations. A weakening ridge of high-pressure gets overrun with clouds on Sunday but not much moisture is associated with this overriding weak system. Frigid temps settle in across the region with upper mountain high temps well below zero all across the eastside. High temps forecasted at Showdown of -15F, with the warm spot at Big Sky at -10F. Light north winds continue. Frostbite concerns, no doubt.   

Below: The latest high resolution HRDPS model run animation for Thursday through 5AM Saturday morning pretty much says it all, this is a BIG storm encompassing a large swath of Montana.

 

Below: The latest Euro model picks up at 5AM Saturday showing snow continuing to accumulate across SW Montana where Big Sky, Bridger Bowl, and Red Lodge will see additional accumulations through Saturday night.

 

West and East of the Continental Divide: 

An arctic high-pressure ridge will strengthen keeping dry but dangerously cold surface temps and wind chills across the Treasure State on Monday and Tuesday 1/30 and 1/31. A few overriding disturbances will begin to infiltrate the Northern Rockies on Wednesday and Thursday bringing a rapid warm up to just below seasonal average temps along with chances of light accumulations. Unsettled skies are looking likely Friday 2/3 into the following weekend.  

Below: The Euro model for surface temps beginning 4AM Saturday 1/28 until Wednesday 2/1. The green shades represent the arctic air and you can see how it spreads through Montana Saturday through Monday. Slight modifications on Tuesday before surface temps return to near normal by next Wednesday 2/1.  

Thanks for tuning in, my next update will be on Saturday, 1/28.  

Powder Out – 

Bob