Dec 24, 2016 @ 6:42 am

The current avalanche danger for West Central Montana is CONSIDERABLE on steep wind loaded slopes and and a MODERATE avalanche danger exits on all other slopes.

Good morning, this is Logan King with the West Central Montana Avalanche Center’s avalanche advisory for Saturday, December 24th, 2016. This danger rating does not apply to operating ski areas, expires at midnight tonight and is the sole responsibility of the U.S. Forest Service.

Weather and Snowpack

A storm system started working it’s way into the region yesterday afternoon and has deposited a trace to 2 inches of snow across West Central Montana so far. Mountain temperatures this morning are hovering in the low 20’s and winds are currently out of the east to south east and sustained in the teens at Point Six and Deer Mountain.

Yesterday Travis and I rode into the Swan Range and found scoured ridges and firm wind affected snow lying across steep slopes with facets and unconsolidated snow at the bottom (Video). We opted to find some safer terrain to travel on and relocated to the Missions. We found the snow in the Southern Missions to be similar to conditions in the Rattlesnake earlier this week, and the primary concern will continue to be windslabs.

There is abundant evidence of wind affected snow throughout the advisory area and features that have wind deposits will be sensitive to triggers. Be very cautious of wind affected terrain and continue to reevaluate wind and how it is affecting conditions throughout the day as wind intensities and directions are projected to change today.

The facets in the snowpack have been gaining strength but we are still finding facets and depth hoar that continue to fail near the ground. Avoid terrain where facets and persistent weak layers exist if there is any cohesive snow sitting above them even a slight density change the cohesive snow continues to act as a slab sitting on the week facets and propagate failures readily. The facets are most prevalent in areas where a shallow snowpack exist, and continue to be reactive and propagate in stability test (Video).

With the season in full swing, now is a great time to brush up or further develop your beacon skills. The beacon park is up and running at the Driftriders Hut outside of Seeley. We will provide updates as our other beacon parks get set up for you to practice on or break in that new beacon you got this holiday season.

Avalanche and Weather Outlook

Mountain snow and wind looks to develop through today bringing anywhere from 3-10″ inches of snow by tonight. Watch the falling snow as it will add stress to the snowpack and if significant accumulations occur give the snow some time to settle and adjust to the new load. Snow will continue through tonight and into tomorrow morning but accumulation rates will begin tapering off over night.

I will issue the next advisory on Tuesday, December 27th, 2016.

Happy Holidays, ski and ride safe.


Problem 1 - Windslabs

  • TYPE


    Wind Slabs

    Release of a cohesive layer of snow (a slab) formed by the wind.  Wind typically erodes snow from the upwind sides of terrain features and deposits snow on the downwind side.  Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

  • SIZE


    2-3 (Large)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

Windslabs have not bonded well to the existing buried layers of facets.

Problem 2 - Facets

  • TYPE


    Persistent Slabs

    Release of a cohesive layer of soft to hard snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks.  Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Persistent, Deep-Slab.

  • SIZE


    1-2 (Small-Large)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

Facets near the bottom of the snowpack continue to be reactive and propagate in stability tests when there is even the slightest of cohesive layers higher up in the snowpack.



Snow will develop through tonight and will start to taper off Sunday morning. Significant winds will accompany the system with varying directions.

This information is the sole responsibility of the Forest Service and does not apply to operating ski areas. The avalanche danger rating expires at midnight tonight but the information can help you make a more informed decision regarding travel in avalanche terrain for the next few days.

Our advisory area includes National Forest System lands in the Bitterroot Mountains from Lost Trail Pass north to Granite Pass, the Rattlesnake Mountains north of Missoula and the Southern Swan and Mission Mountains near Seeley Lake, MT. Avalanche information for the Lookout Pass/St. Regis Basin area is available from the Idaho Panhandle Avalanche Center.