Above 2,500ft Considerable
1,500 to 2,500ft Considerable
Below 1,500ft Moderate
Degrees of Avalanche Danger ?
Problem #1: Persistent Slab
Distribution: All aspects, especially wind loaded slopes and cross-loaded terrain features, treeline and up. Cold weather and wind loading over the last 2 weeks has created layered hard slab in the alpine with lots of weak, facetted snow underneath. There’s also an old rain crust 60+cm down which is beginning to facet. We’re seeing easy failures and propagation on these layers, and this danger will persist for a while. These slabs are underneath the new snow, so you’ll need to be thinking about deeper layers and digging to assess them. It would be wise to avoid slopes 30 degrees and steeper. This is a dangerous time to be in avalanche terrain.
Problem #2: Deep Slab
Distribution: Isolated, on wind-blown slopes with thin snowpack less than 1m thick. Generally around ridgelines, and anywhere rocks are exposed or thinly buried. All aspects. Elevations above 3000ft. In the Pass zone, there are extensive weak facets at the ground in any areas of thin snowpack. We’re now seeing natural slides on this basal facet layer in areas north of the Pass (see photo). Even in places with deeper snow, there remain trigger points near rocks/thin areas. If you were to trigger a slide on this layer, it would be a deep, wide, hard slab avalanche with deadly consequences. This is a low-probability high-danger situation that is very difficult to manage, so it’s best to exercise caution. Be very careful to avoid rocky trigger points and thin areas. Stick to slopes with a deeper, more uniform snowpack.
Recent Avalanche Activity
The last observed avalanche activity was during the last storm cycle Feb 11-15th. There was a natural avalanche cycle within the new storm snow, with widespread D2-D3 slides on all aspects. These were dry slabs above 4000ft, and some nasty wet slabs below that level. A few large avalanches occurred, with crowns up to 2m tall. Some slides hit the valley floors and lower runouts.
Snow totals from Monday were 8-18″ (lower amounts toward the border). An additional 3-8″ is likely Tuesday, with 4-8″ additional on Wednesday. Moderate north winds will be continuing with alpine temperatures 5-15F. Snow will taper off Thursday and Friday, with some clearing possible Saturday.
Additional Info & Media
This is an important time to practice good group management skills and risk-reduction. This means keeping your group spread out while traveling in avalanche terrain. Ride one-at-a-time in any areas of risk, and only group up in safe zones well out of harms way. Evaluate each slope carefully, have an escape route, and a plan for what to do if an avalanche occurs. Always make sure every rider has a beacon, shovel, and probe, and knows how to use them.