Turnagain Pass

If you are headed to Turnagain Pass you get to start your day with a red flag warning, a recent avalanche. Yesterday two skiers remotely triggered an avalanche on the Southwest face of Eddies from 30’ away on a flat ridge. They had just dug a pit and found the culprit, buried surface hoar, one foot below the surface. Multiple tracks were present along the ridge before the avalanche released no obvious signs like whumpfing were observered.

This is the same buried surface hoar “MLK BSH” we’ve been talking about for two weeks since it was originally buried on Matin Luther King Day. This weak layer is widespread across our forecast zone and has been responsible for numerous large human triggered avalanches over the last 10 days, all in Seattle Creek drainage, and not visibile from the road. So far no one has been caught or carried and most of these avalanches have been triggered remotely from an adjacent ridgeline. Yesterday was the first human triggered avalanche on the non-motorized side of the road. Today’s sunshine and soft snow could make it tempting to push into steeper terrain. Keep in mind incremental loading over the last week and period of stronger winds on Monday may have added more stress to this weak layer. Don’t forget this is a challenging avalanche problem to evaluate and manage, and warrents extra caution.

Keep in mind as you travel today:

1. The weak layer is around 2-3 feet under your feet or snowmachine, but triggering this weak layer will be more likely in a thinner part of the slab.
2. No obvious signs of instability like “Whumpfing” are expected until a slope releases.
3. Previous tracks on a slope do not mean its safe. The 2nd, 3rd or 10th person could find a thin spot and trigger a large slab that propagates across an entire slope.
4. Remotely triggering a slab from the ridge, sides or below is possible.
5. Use safe travel protocols: One at a time in avalanche terrain, Stop in safe zones, Watch your partners and Avoid terrain traps.
6. Assess the consequences if the slope slides. The larger the terrain = the larger the potential avalanche!

South of Turnagain – Johnson Pass/Summit Lake zone: Areas south of Turnagain Pass harbor a thinner, weaker snowpack with multiple weak layers present, including the MLK buried surface hoar. This area also received additional snow on Sunday and Monday and elevated Easterly winds. Similar to Turnagain Pass an avalanche triggered in this zones could propagate an entire slope and be large enough to bury or kill a person.

Remote triggered avalanche on Eddies occured yesterday afternoon after mulitiple people had skied the ridge.   

CORNICES: We had a report of a large cornice fall in upper Seattle Creek drainage over the weekend. Give cornices an extra wide berth as they often break farther back than expected.

LOOSE SNOW AVALANCHES (dry and wet): Daily warming and radiation from the sun could warm surface snow on steep Southerly aspects. Keep your eye’s out for roller balls or small wet-loose avalanches under rocks. On shaded aspects dry loose “sluff” is possible in steep terrain.

WIND SLABS: There is a lot of snow available for transport. Ridge top winds should remain light from the Southeast, but winds could puff up along some localized upper elevation zones. Should you see drifting snow, expect any recently wind loaded feature to be tender. Any wind transport will also be adding stress to a larger more dangerous avalanche problem, where triggering a small wind slab could step down into a deeper more dangerous layer.

Glide cracks are opening again. We know of one glide avalanche that has released recently in the Summit zone just north of Manitoba. Look out for glide cracks and limit exposure under them!