Turnagain Pass

Many large natural avalanches occurred yesterday during the peak of the storm. Despite the poor visibility, one backcountry skier witnessed a ‘huge powder cloud’ across Turnagain Arm while he was driving around 4pm yesterday. This was off the peak on the west side of Seattle Creek drainage (west of Pyramid Pk). A group ice fishing on Carter Lake heard the rumble of a large avalanche, 45 seconds of rumbling, late Sunday night off Wrong Mountain in the central Kenai Mountains. There were other naturals evident from new debris piles, some of them quite large, in the bottom of slide paths that could be seen from roads.

Debris from a large natural avalanche that occurred yesterday along the Seward Highway. 12.6.21. 

Avalanche in motion in Portage Valley, across from the Visitor’s Center. This slide was triggered by artillery during avalanche hazard reduction work. 12.6.21.

The warm storm system that moved in Sunday, peaked yesterday, and is moving out this morning as we speak. Right on its heels however, are strong northwest winds that will usher in not only cold air, but clearing skies. By early afternoon ridgetop winds are slated to be blowing 25-35mph with gusts into the 50’s. This wind direction is completely the opposite from the storm and will likely be transporting a fair amount of new snow into sensitive wind slabs. Areas seeing the strongest winds are expected to also see natural wind slab avalanches. These wind slabs could step down into buried weak layers, creating a much larger avalanche.

Storm total estimates at 2,500′ beginning Sunday:
Girdwood Valley:  15-20″ snow (1.7″ of water equivalent)
Portage Valley:  2-3′ snow (2.5″ of water equivalent)
Turnagain Pass:  14-18″ snow (1.5″ of water equivalent)
Summit Lake:  10-14′ snow (1″ of water equivalent)
Lost Lake/Snug Harbor:  2-3′ snow (2.5-3″ of water equivalent)

The most dangerous places for us to be are either those that saw the most snow and/or those that will see the strongest winds today; that will be the south end of Turnagain Pass, Summit Lake, Snug Harbor, Lost Lake, among others. It’s a day to really watch the winds, but also know the snowpack itself can’t be trusted. If you are in an area with little wind, you could still be walking into a trap with those buried weak layers discussed below.

Low visibility at Turnagain Pass yesterday. This is looking at the lower slopes of Seattle Ridge from the motorized parking lot. 12.6.21.

It is a glaring sign that the weak layers down in the snowpack are still quite reactive when a storm that only had a couple feet of snow with strong winds created such large avalanches. For backcountry traveling, this is a really big concern as the weak layers (facets and buried surface hoar) are now further down and any avalanche triggered could be very large and destructive. Furthermore, these weak layers have been propagating long distances, and people have been triggering avalanches remotely- from above, below, and to the side of steep slopes.

All that said, the heart of Turnagain Pass didn’t see the ‘feet’ of new snow other places did, but we still have to be on our guard. With no visibility yesterday, we have no information yet as to natural avalanche activity. With winds today being a bit of a wild card here (meaning the northwest direction can sometimes miss parts of Turnagain) we have to assume it is as dangerous as it was last week.

This will be a great day to simply avoid any avalanche terrain and play in the flats and on slopes 30 degrees or less with nothing steeper above you. If you are at Turnagain Pass and find little wind and only a foot of so of new snow, the danger is more toward CONSIDERABLE. Be sure to have a cautious mindset, as triggering an unsurvivable slab in buried weak layers is still a very real possibility.