Turnagain Pass

The last avalanche within our advisory area was a large remote-triggered avalanche north of Girdwood last Tuesday. This was the latest of 18 very large human-triggered avalanches over the past 9 days, all of which we suspect were failing on the layer of facets that was buried on 3/14.

There are two main problems to watch out for today, and it is hard to say which one should be at the top of the list. The most likely avalanches will be failing up to a foot deep or so where strong easterly winds are going to build fresh wind slabs today. Less likely, but much more scary, is the potential for triggering a massive avalanche failing deeper in the snowpack. More on that in Problem 2.

Winds are expected to be light this morning but increasing through the day, with sustained speeds of up to 30 mph and gusts to 40 mph by this afternoon. These strong winds will form a fresh round of wind slabs that will be especially reactive this afternoon. These are most likely to be found just below ridgelines, in cross loaded gullies, and on convex rollovers. There are a few clues you can use to look for unstable snow. From a distance, be on the lookout for snow blowing off ridgelines as a key indicator that fresh slabs are forming at higher elevations. As you travel, you can spot unstable conditions by watching for cracks shooting out from your skis or snowmachine, or by using small test slopes to see how the snow surface is reacting.

Keep in mind, these fresh wind slabs will be adding load to a snowpack that has produced multiple very large avalanches failing on an older weak layer buried 3-6′ deep. We are still dealing with a scary snowpack setup, and that is giving us cause to stick to lower angle and low consequence terrain for now.

It is likely a person will be able to trigger an avalanche similar to this snowmachine-triggered avalanche as winds ramp up through the day. Photo: Warren Gage, 04.01.2023

Watch for snow blowing off ridgelines as a sign of increasing avalanche danger in the upper elevations. 04.01.2023

As we move further away from our last major loading event, the snowpack has had more time to adjust and the weak layer that was responsible for all of the huge avalanches over the past 9 days has become more stubborn. It has now been 6 days since the last known avalanche on this weak layer. Based on what we’ve been seeing in snowpits over the past week (details in our observations from Girdwood, Sunburst, and Magnum), we know that weak layer of concern is still there lurking well below the surface. For now, that scary setup has us avoiding traveling on or below steep slopes. The likelihood of triggering an avalanche is decreasing, but the consequences are just too high to mess with it. We have seen multiple avalanches triggered remotely from low-angle terrain connected to steeper slopes, and these monsters are running far into lower elevation runout zones. The layer is slowly gaining strength, but we are not ready to trust it yet.

This avalanche is the kind of thing that we are still concerned with. The avalanche was triggered over a week ago and it is becoming less likely, but the setup is still there and it has our attention. 03.25.2023