Turnagain Pass

Very strong “outflow” winds impacted the region yesterday. Cold arctic air rushing down from the North battered the mountains. What soft snow did remain after the Dec 30th wind event was likely taken away with this Jan 5th wind event – a bit like salt on the wound! We only know of one small natural wind slab that released on an Easterly aspect in the Summit Lake area yesterday. Otherwise, there was just too little snow available for transport to produce natural wind slab avalanches. 

For Today:  Watch for new wind slabs from yesterday, overnight and today (winds are forecast to be moderate from the North and West). These slabs are likely to be shallow, very stiff and could surprise you on a steep slope. Watch for these in any location with wind loading, including lower on slopes. These also have the potential to overload buried weak layers and produce a much larger and dangerous avalanche. The Easterly face of Seattle Ridge is an example of where winds have been loading and known buried weak layers exist.

Safe travel protocol is your friend and if you head out today, remember to expose one person at a time, watch your partners, have an escape route planned and group up in safe zones.

Significant wind transport along Wolverine Ridge (seen from Portage). Winds along this ridge were more Southwesterly due to “terrain forced flow” in complex topography. 

The Summit Lake and Kenai Mountains got hit as well with these impressive winds. Below are plumes coming off the Southwest shoulder of Silvertip Peak (far left). 

Although the snowpack is wind hardened and tired, it does have a poor structure. There are a variety of weak layers in the middle of the pack as well as at the bottom. The slab on these weak layers is quite variable and hard – and though difficult to trigger, the possibility does exist. Steep wind loaded slopes (Northern and Eastern) that haven’t avalanched yet are the most suspect. Likely trigger spots are in thinner areas near rocks. Obvious signs like cracking and ‘wumpfing’ are becoming less common, making it more difficult to assess slope stability. Heavier loads, such as snowmachines or large groups of people can also be a trigger. 

In the periphery areas (Girdwood, Johnson/Lynx Creek and Summit Lake) where a thinner snowpack exists, several observers have experienced collapsing/wumpfing in recent days. 

Believe it or not, 3 glide avalanches have occurred in the past 5 days in the Turnagain Pass zone. These are SE aspect of Lynx Creek, SE aspect of Seattle Creek, and the SW face of Eddies. Along with recognizing wind affected snow, keep an eye out for glide cracks and limit time under these. They can have a knack for releasing during cold weather.