Turnagain Pass

There have been multiple observations of wet slab avalanches releasing during the heat of the day over the past few days, with the most notable being the W to NW facing avalanche path on Orca in Girdwood. There were multiple start zones that released at elevations ranging from 2000-2400′ on SW through W aspects. The debris ran out to treeline on a NW facing avalanche path all the way down to roughly 300′ in elevation.

Overview of massive wet slab avalanche that released in multiple start zones near 2400′ and ran full path down to roughly 300′. Photo 4.26.24

It is a classic ‘springtime conditions’ type of day, where avalanche danger will start off low while the snow surface is frozen and gradually increase on sunny aspects as the crust starts to melt and wet avalanches become likely in the afternoon. The clear skies and temperatures dropping to freezing level or below overnight should create a very strong crust. How quickly the crust will soften, and avalanche conditions will become more dangerous, will depend on aspect and elevation. Eastern aspects will start to soften first, followed by southern aspects, and then western aspects in the afternoon. At upper elevations temperatures are cooler and light east winds might help keep the surface crust intact later into the day.

Wet slab avalanches are the biggest concern today because they can be very large, destructive, and unpredictable. The large wet slab avalanche that released on Wednesday on Orca in Girdwood is a good reminder of the potential size of these avalanches and how unmanageable they are if a person is caught in one. The best way to avoid these conditions is to monitor the snow surface conditions and look for any wet loose avalanches or roller balls releasing naturally, which can be a precursor to wet slab activity. Another rule of thumb is to move onto a shadier aspect once your boot starts to sink in more than ankle depth.

Wet loose avalanches are also likely as the surface starts to soften and can become quite large if they run down long slopes. Be aware of other groups that might be below you to avoid having a small wet loose avalanche triggered up high becoming a potentially dangerous situation for folks further down slope.

Glide avalanches and cornice fall are also a normal part of the spring shed cycles. These tend to be less predictable hazards in terms of timing, but are most likely to release during the heat of the day. The best way to avoid these hazards is to simply avoid spending time underneath open glide cracks or large corniced ridgelines. Giving cornices a wide berth when you are traveling on a ridge is also a wise move when they are getting direct sunlight.

Close up of the wet slab crowns that released on the SW face of Orca near 2300′. Photo from 4.26.24