Jan 3, 2018 @ 6:29 am

Good morning, this is Logan King with the West Central Montana Avalanche Center’s weather and avalanche update for January 3rd, 2018. 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

Temperatures at mountain locations vary from 15 to 31 degrees this morning. Winds at Point 6 are 17mph gusting to 21mph from the W and at Deer Mountain are 8mph Gusting to 12mph. A trace to 4 inches of snow has fallen in the last 24 hours across the region.

Wind slabs remain the primary concern today. The secondary concern is persistent weak layers. Wind slabs have continued to produce avalanches that are stepping down to the facets on the Thanksgiving crust. The combination of a stiff windslab and the added stress of wind loading continues to be able to trigger this weak layer. These avalanches have been large high consequence events and should be treated with respect. Be cautious of wind loaded terrain near ridge lines and keep an eye out for cross-loaded pockets that can sneak up on you.

Light snow this morning will subside and mountain temperatures will be in the low 30’s. Snow looks to return to the area on Friday.

If you are out in the backcountry, please send us your observation, these are very helpful in producing the advisory. The next advisory will be issued tomorrow January 4th, 2018.

Ski and ride safe.


Problem 1 - Wind Slabs

  • 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 (Large)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

Wind loaded terrain continues to produce large avalanches.

Problem 2 - Persistent Slabs

  • 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


    3 (Large-Very Large)

    The potential size of avalanche resulting from this problem.




    The likelihood of an avalanche resulting from this problem.

The facets associated with the Thanksgiving crust are hard to trigger now that they are buried deeper but are reactive in areas with wind loading.


Light morning snow will give way to warming temperatures at upper elevations. The next system will move into the region around Friday.

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.