Above 2,500ft Moderate
1,500 to 2,500ft Low
Below 1,500ft Low
Degrees of Avalanche Danger ?
Problem #1: Wind Slab
Distribution: Generally on south-ish aspects and cross-loaded terrain features, treeline and up. We had a north wind event on Saturday, with some brief but intense snow transport over ridgelines and exposed areas. Any areas of recent wind loading will have cold, dry hard slabs that need to be avoided. Stick to the wind-sheltered areas where the snow is still soft.
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 haven’t observed avalanches on this layer yet, but there remain trigger points in areas of thin snowpack or rocks. 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.
Excellent weather continues Monday, with light winds, mountain temperatures 16-25F, and plenty of sun. A low will set up offshore and slightly to our south, and will try to push a couple of fronts into our area Tuesday-Thursday. At this time, it looks like offshore flow will be strong enough to dry out the fronts and keep them to our south, so accumulations are expected to be less than 6″.
Temperatures have been well below freezing, and winds light since our last storm on the 15th.
Feb 11-15th brought a pretty exceptional storm cycle. It started with 10-15″ of cold, weak, low-density snow, with another 10-15″ of heavy, wet snow above. This led to poor bonding within the new snow. We then had a significant rain-on-snow event on the 13th, with up to 2″ of rain falling below 4000ft. Rain reached up to 5000ft for a brief period. The cycle finished up with a nice shot of cold air and nice, fluffy snow 12-18″ on top of the saturated wet slop below. Temperatures dropped to 10-20F on the 16th as the storm cleared out.
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.