Upper Headwaters

We rode and skied into the site of the January 4th, 2025 snowmobile triggered avalanche in the Upper Headwaters of the Salmon River to investigate the avalanche. While riding in, we documented an additional 6 recent slab avalanches that had all failed on E/NE aspects. We observed a couple of very small local collapses above 8000 feet in protected low-angle terrain.  Snow depths increased to nearly 6.5 feet (190cm) as we climbed in elevation. This area appears to be one of the deepest locations within our forecast area.

Avalanche specifics can be found in the avalanches tab.

We went in to investigate the large snowmobile triggered avalanche in Upper Headwaters. We also observed a variety of smaller recent avalanches during our way in/out (documented below). Only a couple of very small local collapses and no cracking observed during our tour.

New Snow: We found 2-8" (5-20cm) of recent new snowfall as we travelled up in elevation throughout our tour. 

Persistent Weak Layers: We were able to track weak snow buried below the recent significant post-Christmas storm snowfall with pole probing as we moved up the drainage. The layer of concern is primarily facets below the 12/13 crust and this layer is widespread (found on all aspects at mid and upper elevations). In our snow profile near the S flank of the large snowmobile triggered avalanche, we found a relatively simple snowpack structure:

• A nearly 4 foot (115cm) thick slab above the 12/13 crust comprised of 3+ feet (90cm) of post-Christmas storm snow
• Weaker old faceted snow below the crust that propagated in a propagation saw test (PST 47/130 END) but did not fail in an extended column test (ECTX on deeper facets)
• The slab is now thick enough in many places that ECT tests are no longer reliable to test the layer of concern (buried >100cm)

Snow Depths: Probing around in undisturbed snow in the avalanche runout (~9000 feet) revealed snow depths of 150cm - 170cm. Where the debris was deposited, we found depths up to 240cm. Snow depths appear to increase in the 500 feet of additional elevation towards the ridgeline, probably due to wind-deposition nearer to the ridgeline. The crown of the avalanche appeared to be 4-6 feet deep, further reinforcing the additional snow depths in near-ridgeline locations.