Turnagain Pass

The recent storm deposited up to 3′ of snow in the Alpine and had sustained winds in the 30-40s. There is evidence throughout the terrain of cross and top-loading. It is possible to trigger an wind slab in steep leeward terrain. Look for cracking, listen for hollow sounds and avoid stiff, pillowed snow. In addition, there is a lot of snow available for transport if the winds pick up at all today. There were a few small human triggered wind slab avalanches observed in the Tincan Common Bowl and along CFR ridge yesterday.

Winds and new snow have also added to already large cornices. These are quite hazardous, they often break much farther back than expected and can trigger avalanches on the slopes below. This happened throughout the region last weekend.

 Yesterday a snowmachine triggered a cornice fall and took an unexpected dip off the ridge into Warm-up Bowl (-1 Bowl).

We are continuing to investigate how the recent storm has bonded to the old snow surfaces, especially areas that may harbor persistent weak layers and rain crusts. Last weekend there was a large snowmachine triggered avalanche in Groundhog Creek, in the Johnson Pass region, that ran on buried surface hoar. We do not have recent information from that area and that layer may still be reactive. 

This last storm also may have buried a newer layer of surface hoar formed last weekend and/or faceted snow resting on the 1/27 rain crust. These layers were reactive during the storm but we did not observe human triggered avalanche activity on these layers yesterday or have concerning stability test results. Observers were reporting good bonding at the old snow/new snow interface and to the 1/27 rain crust. However, we are not ruling out the possibility of triggering an avalanche on a persistent weak layer today. Look and listen for whumpfing, collapsing and cracking, these are snowpack red flags that indicate unstable snow. Avoid thin spots, steep convexities and rocky areas. These are all possible trigger points in the terrain. This type of avalanche problem may be triggered by the 1st person on the slope or the 15th. It is important to not overload slopes with multiple riders all at once.

Glide cracks still litter the terrain in the Treeline elevation:1000′ – 2500′. New glide cracks continue to appear. Travel underneath should be avoided. They are totally unpredictable, regularly releasing and producing glide avalanches that would be unsurvivable. Yesterday a high mark was observed on Seattle Ridge directly underneath one. Scope out the terrain you want to travel in to avoid this type of exposure. 

Photo: glide crack on Petes South