The December 20 advisory from the West Central Montana Avalanche Center rates avalanche danger as "High" in the backcountry. The rating does not apply to ski areas and will be updated as conditions change. Logan King of the center reported "considerable" danger on non-wind-loaded hillsides. Logan reported wind slabs as the main concern, with skiers triggering slides in the Blackfoot and in the Bitterroot Mountains. Wind slab movements can be large and you are in danger if you are are on, below or just nearby such a feature.

King said if you see signs of wind loading, listen for "whumpfing," and look for shooting cracks, and collapsing areas of snow. The West Central Avalanche Center has an area where you can report your observations. The advisory area includes National Forests 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.