Turnagain Pass

Blue skies, light winds and chilly temperatures are on tap for this New Year’s Day; what a great weather forecast to bring in the New Year and not to mention, we have 13 more minutes of daylight since solstice! With nothing weather-wise to increase the avalanche danger, we are looking at a few existing snowpack issues that should keep us on our toes. These are lingering wind slabs and some funny business buried in the snowpack, discussed below.

First wind slabs. Over the past 10 days the mountains have received quite a bit of wind. Winds have been from our standard easterly direction and the most recent winds that formed slabs were two days ago. Hence, wind slabs, wind crusts and scoured areas are common above treeline. With folks headed into the further reaches of the forecast zone and beyond, there are sure to be a few wind slabs that could still pop out on us. Watch for hard snow over softer snow and any cracks that shoot out from you. Wind slabs generally have a smooth rounded surface where snow has been piled up. Be suspect of these pillowed areas on the steep slopes, rollovers and in steep gullies.

In addition, on steep slopes with only loose surface snow, keep an eye on your sluff, as usual. Also, don’t trust cornices. Always give them a wide berth and limit time under them

Wind effect on Pyramid Pk at Turnagain Pass. Soft snow can be found, but there is definitely a high degree of hard wind packed snow in the Alpine zones. 12.31.20. Photo: Peter Wadsworth

Old natural wind slab avalanche in one of the Seattle Ridge headwall chutes. 12.31.20.

As we’ve been mentioning for several days now, at the mid elevations (1,000 – 2,500′) there is the old December 1st crust that continues to degrade. It is 3-5′ below the surface and between 1-4″ thick. It is slowly metamorphosing (changing) from a strong crust into a faceted weak layer and crust combination. This is happening quicker in some areas than others. For example, we’ve found it more concerning on the non-motorized side of Turnagain Pass and in Girdwood Valley. Just yesterday, this crust/facet combo was the culprit in another large 6′ deep explosive triggered avalanche in Girdwood Valley. Although it is still unlikely a person could trigger one of these large slabs at these mid-elevations, we need to keep it on our radar. Whumpfing will be a sure sign you’ve found some weak snow beneath your feet.

A lot of folks have been getting out in the Summit Lake region to the south of our forecast area. Here, not only is this December 1st crust/facet combo a concern, but other mid-pack weak layers and even the basal facets on the ground in the Alpine continue to show weaknesses. In general, the snowpack is thinner and weaker and along with other shallow zones (Silvertip for example) it is worth keeping these old weak layers in mind before pushing into bigger terrain.