Turnagain Pass

No new avalanches were reported yesterday. The last known avalanche was a large skier-triggered avalanche on a steep southwesterly rollover on Eddie’s on Saturday. The avalanche likely failed at the 2/5 storm interface, which would have had a crust on the bed surface at that elevation.

It’s looking like we’ve made it through the worst of this outflow event with minimal damage in Girdwood and Turnagain Pass. That said, with sustained wind speeds of 10-15 mph and gusts near 30 mph for the past 12 hours, we can expect to find reactive wind slabs at the upper elevations today. The mountains hit hardest by these winds tend to be close to the Turnagain Arm, Summit Lake, and especially Seward and Lost Lake with this round of weather. It is looking like visibility will be good enough to get up high today, so pay attention to increasing avalanche danger as you gain elevation. You can expect to find unstable snow near ridgelines, below convex rolls, and in steep cross-loaded gullies. The northwesterly winds will load terrain differently than our more common easterlies, so be on the lookout for dangerous wind slabs in unusual places.

Fresh wind slabs are easy to recognize as you travel if you are paying attention. Watch out for stiffer snow on top of softer snow, and take special note of cracks shooting out from your skis or snowmachine. It can be incredibly informative just taking a second to hop off your snowmachine or take a few steps off the skin track to look for those stiffer wind slabs. Remember, the wind has been loading a snowpack with weak layers near the surface, which makes larger avalanches possible. More on this in problem 2.

Cornices: Along with these strong winds come fresh and sensitive cornices. They may be forming in weird places with the northwesterly winds, so keep your eyes open while you are traveling. Be sure to give them plenty of space as you travel along ridgelines, and minimize time spent traveling below them.

There is still a lot of uncertainty with the interface below the 2/5-2/6 storm, now buried 1-2′ deep. At elevations below around 2000′, there is a thin crust at this interface that was likely a contributing factor in the most recent avalanche on Eddie’s. At upper elevations, we saw storm slab-type activity lasting just a little longer than usual following the storm, so we are still treating this as a layer of concern. The layer is a tricky one to assess, since it has now been affected by two different wind events so the depth can vary greatly. The best way to see how the interface is behaving is to dig down and look, but the easiest way to manage the problem is to step back your terrain use for now until that layer has healed.

In addition to the 2/5 interface, that deeper layer of buried surface hoar from January 10 is still lurking down there around 3-4′ deep. It is becoming really unlikely that a person will trigger an avalanche on this layer, but we are still keeping it on the radar for now. With fresh wind loading today and another round of snow and wind expected tomorrow, extra weight is adding stress to the snowpack. This will nudge any buried weak layer closer to its breaking point. One more reason to be a little more conservative with terrain today.

In the past 24 hours we’ve added another fresh layer of wind slabs on top of this sandwich. There is plenty to look out for in the upper snowpack right now. 02.09.2023

The weak snow near that Thanksgiving crust is still sitting there near the bottom of the snowpack. For most of the advisory area, a human-triggered avalanche on this layer is very unlikely. There may still be some thin spots where the weight of a person could trigger an avalanche, especially at the south end of our advisory area around Silvertip and down towards Summit.