Turnagain Pass

The only avalanches we heard of yesterday were two glide releases on Seattle Ridge, one of them pictured below. There were no known human triggered avalanches. The last avalanches seen/reported were from Saturday and Sunday when a widespread natural avalanche cycle occurred during the Holiday storm that deposited 2-3 feet of snow with strong east winds.

Recent glide avalanche, likely released Dec 24 or Dec 25. Photo by Andy Moderow 12.25.23.

It was two days ago this morning when the Holiday storm ended along with the end of the dramatic natural avalanche cycle. Because there were so many avalanches from Girdwood to Turnagain Pass and to Summit Lake, we are suspect that the storm snow didn’t bond well and could still be an issue. With a bump in winds today, there will be two avalanche issues in the top 3 feet of the snowpack:

Lingering Storm Snow Avalanches:  The Holiday storm snow fell on loose older snow with a layer of surface hoar on top. That surface hoar is now buried 2-3′ deep and we don’t yet have a good handle on how big of a problem it may be in the snowpack. Yesterday on Tincan, a skier around 3,000′ in elevation triggered a whumpf big enough that their partner felt it along with another group 300′ away. This is bulls eye data that the snowpack was not stable and the group stuck to low angle terrain. If this type of red flag continues, then we have to expect we can trigger avalanches on any aspect at elevations above 1,500′, where that new crust disappears. It might be too deep to do simple hand pits to assess this layer, and even if we could these types of layers are often hard to assess anyhow. Sticking to the smaller terrain and mellower slope angles, away from large committing slopes, is a good way to stack the odds in our favor. Please if you get out, let us know what you see, or don’t see!

New Wind Slabs:  There is some discrepancy with the weather models on how strong the NW winds will be this morning and the SE winds this afternoon. The key will simply be to pay close attention to any wind effect on the snow surface and/or if you are seeing active wind loading. Fresh wind slabs should be shallow, maybe up to a foot thick. However, this issue will be forming on top of the storm snow issue just mentioned. Hence, any new wind slab could be more dangerous than expected if it steps down and triggers a larger storm slab below.

The storm warmed up on Sunday and rained as high as 1,500′ in places. Reports yesterday stated that a rain crust sits under 2-6″ of loose snow and goes away around 1,500′.

Tincan on Christmas Day during a moment of sun hitting Seattle Ridge. Not a lot of folks were out and parking, as of yesterday afternoon, was still very limited and many areas remained unplowed. 12.25.23.

Glide cracks are opening up and continue to release every now and again. There were two new glide avalanches seen on Seattle Ridge yesterday that likely released in the past two days. As the photo below shows, some ridgelines and slopes are littered with cracks. If you see these, it’s always best to avoid being under them. They can release into an avalanche at anytime.

Glide cracks covering the steeper slopes of the north end of Seattle Ridge. Photo taken from Tincan by Andy Moderow, 12.25.23. 

Sitting under 4-6 feet or more of snow is that old Thanksgiving crust with facets that were, and maybe still are, forming around it. With hampered visibility again yesterday, we are still waiting to see if any of the avalanche activity from the Holiday storm broke in those facets on the crust. This would have created a very large slide with a big crown face. Due to the depth, the layer is not only very difficult to assess at this point, but also would be very difficult to trigger. We are not forgetting about it however and will continue to look for any evidence that it is reactive.