Hatcher Pass

There were multiple human triggered avalanches this week. Numerous natural avalanches were observed after Monday’s storm. Several avalanches were triggered remotely on Tuesday and Wednesday. 

12/21/21 – Marmot SW Face showing closeup of human triggered avalanche, more details HERE

12/21/21 – Marmot SSE, ~3500′, remotely triggered

Marmot Storm Slab – Naturals 12/20-21

As of 6:30am two inches of new snow have fallen and winds are gusting up to 22mph from the WNW. We anticipate winds to increase throughout the morning. Two storms on Dec 18th and 20th covered Hatcher Pass in 1-2 feet of new snow. This snow is behaving like a slab in some areas. Human-triggered persistent slab avalanches are likely at all elevations and on all aspects. Natural avalanches are unlikely. These avalanches will be small to large in size. Persistent slab avalanches will be possible on slopes that are 30° or steeper. It will be possible to remotely trigger avalanches adjacent to or from below a slope.

Right now we have a textbook set up for persistent slab avalanches. November’s cold weather that created widespread sugary faceted snow, has come back to haunt us. Two storms in the last week have now buried this weak layer. This faceted snow is the weak layer responsible for several human and remotely triggered avalanches on Tuesday. Stability for this avalanche problem will improve slowly with time. Use pole/probes and formal instability tests to identify areas with a cohesive slab sitting over weak sugary facets. Whumping and shooting cracks will be red flags for this avalanche problem.

Persistent slab avalanches are a difficult problem to manage even for seasoned backcountry users. On Tuesday, avalanches occurred after several riders had already traveled down  slope. Previous tracks are not an indicator of stability with this avalanche problem. 

Old hard slabs still exist in some areas and are now covered in low density snow. Hard slabs are capable of breaking above you making escape difficult. Space out when ascending slopes, descend slopes one at a time, and make sure you regroup in areas that are out of harm’s way. Avoid traveling and riding above terrain traps, which can increase the consequences if you are caught in an avalanche. We anticipate poor visibility in Hatcher Pass today, it will be difficult to tell if you are traveling underneath avalanche terrain or remotely trigger an avalanche.

We’ve seen a lot of people traveling in the forecast area the past few days. Be aware of other groups traveling above you and avoid riding slopes that others are ascending. Communicating your plan to other parties can go a long way.

12/21/21 – Marmot SW Face remotely triggered

fishhook creek remote triggers 12/20-21

West-Northwest winds are forecasted to increase this morning up to 29mph with gusts up to 47mph. These winds are forecasted to diminish by 12pm. There is a lot of snow available for transport which is currently building wind slabs. Human triggered avalanches are likely on leeward aspects east thru south, at mid and upper elevations. Natural avalanches are possible. These avalanches will be small to large in size. Wind slabs will be 4-8” thick and building throughout the day. Look for freshly formed wind slabs near ridge tops and cross loaded gullies. 

If you do trigger a wind slab it will be possible for it to step down into persistent slab avalanches, increasing the size and consequence of the avalanche. To identify this avalanche problem look for smooth wind drifted snow. Use probes/poles, hand pits, and formal instability tests to look for dense cohesive snow sitting on top of low density soft snow.