Turnagain Pass

A remote triggered avalanche from the Girdwood area was reported yesterday, which released about 2′ deep and took out some old ski tracks. As far as we know no one was caught or involved with this avalanche. These are concerning signs that the old snow interface from early this week still has reactive persistent weak layers that are capable of producing human triggered avalanches. In the Girdwood area this layer is buried roughly 2′ deep, while in Turnagain Pass the layer is likely closer to 1′ deep on the north end of the pass and shallower on the southern end of the pass.

Remote triggered avalanche from Girdwood area. Photo 4.12.24 from Anonymous

Just as we were starting to hope that the layer of buried surface hoar and surface facets that was buried on Tuesday (4/9 interface) was becoming unreactive, we heard about a large human triggered avalanche in the Girdwood valley yesterday. The fact this avalanche was triggered remotely, meaning a person triggered the slide from adjacent lower angle terrain, and that it took out a bunch of old ski tracks are strong signs of a lingering persistent weak layer in the snowpack. The Girdwood area was heavily favored by the snowfall on Tuesday, with 1.5-2′ falling compared to 6-10″ in Turnagain Pass, which means the weak layer is buried more deeply and the potential size of human triggered avalanches is larger in the Girdwood area.

We recommend carefully evaluating how well the snow from this week is bonding to the old snow surface before committing to steeper terrain today. Persistent weak layers can cause avalanches on lower angle slopes than typical and can produce wide avalanches that connect across multiple terrain features. On southern aspects these weak layers are likely sitting on top of a crust, which could make them more likely to produce larger and wider avalanches.

As the sun starts to come out this afternoon it could melt any surface crusts in the upper snowpack, which may increase the potential for triggering a persistent slab 1-2′ deep. Since there is no significant weather stressing the snowpack today we think the chances of natural avalanches are pretty low, however a falling chunk of cornice or wet loose avalanche could act as a trigger for this deeper weak layer. To avoid the problem entirely you can always stick to lower angle terrain.

Another photo of Girdwood area avalanche from 4.12.24

It looks like the sun might wait until the afternoon before making an appearance today, but since it is mid April it doesn’t take long for the sun to start melting the surface snow if skies clear. Keep an eye out for wet snow on the surface and roller balls or small avalanches releasing from solar aspects, especially in thin rocky areas. Wet loose avalanches are typically small, but on large slopes they can pick up a lot of snow on the way down and turn into larger avalanches. You can always switch to a shadier aspect to avoid wet avalanche problems.

Strong sun can also cause cornices to start shedding, and there are a lot of ridgelines still holding onto humongous cornices. Try to avoid spending time underneath cornices if they are receiving direct sunlight and give them a wide berth if you are travelling along a corniced ridge. If you are lucky enough to find some sheltered north facing terrain still holding soft snow, dry loose avalanches are also likely in steep terrain today.

Example of roller balls on steep solar terrain from earlier this winter. Photo 3.21.24