Turnagain Pass

The last known avalanches in our forecast zone were immediately following the Dec 14-15 storm. Multiple large avalanches appeared to have failed in weak faceted snow near the Thanksgiving crust, with the largest avalanches in the Girdwood Valley and on the south end of Turnagain Pass.

HAPPY SOLSTICE everyone!! Starting tomorrow, we’ll have 6 more seconds of daylight to play in than we will today, our shortest day of the year. Today’s solstice will bring with it a few high clouds and an increase in ridgetop winds. Winds are expected to blow 10-20mph with stronger gusts from the east, which could be enough to form new wind slabs in the high elevations. Slabs should be building here and there through the day, so watching for active wind loading will be our best bet to knowing what slopes are being loaded.

Newly formed wind slabs could get up to a foot deep or so and should be easy to see. They may be touchy as they will likely be sitting on weak faceted snow. In shallower snowpack areas such as Lynx creek and outside our forecast zone in Summit Lake, a wind slab may overload buried weak layers. In this case a smaller wind slab could step down creating a larger avalanche.

Dry loose avalanches:  The surface snow is getting looser by the day with the cold temperatures. Sluffs on steep slopes should be expected.

As time goes on, we are still concerned about those layers of faceted snow sitting above and below the Thanksgiving crust. This is our ‘persistent slab‘ problem. These layers create the potential for a person to trigger a slab avalanche, in this case 2-4′ deep. That potential is decreasing with time and in the absence of new loading by snow/wind. The winds today are not expected to transport enough snow to overload these layers in Turnagain, but the Summit Lake area could be different as mentioned above.

The mountains around Girdwood and towards the south end of Turnagain Pass are the most suspect for triggering a persistent slab; along with many areas outside our forecast zone like Chugach State Park. In short, this is a tricky situation, especially as the snowpack slowly stabilizes and triggering one of these slabs gets tougher. Tracks on a slope doesn’t mean that slope is safe, yet at the same time, unless it avalanches we won’t know for sure one way or the other. What we can do is implement good travel practices by exposing only person at a time, watching our partners, or just sticking to the lower angle slopes to avoid the problem.

Many tracks in steep terrain in Superbowl without any skier triggered avalanches. It is easy to forget there is some funny business buried in the snowpack. Debris off the north side of Cornbiscuit in the foreground is from natural activity during the Dec 14-15 storm. Photo taken 12.18.22.