Turnagain Pass

Another glide crack released yesterday in the Crow Creek area of Girdwood. An anonymous observer shared before and after photos with us to confirm the timing. Otherwise we do not know of any recent human triggered avalanches in the forecast area over the past several days.

This avalanche looks small in the photo, but it is likely 3-5′ deep and ran several thousand feet into the valley bottom. Photo from Anonymous 12.29.23

The number of glide avalanche releases that have occurred in the past week is not normal. Typically we have glide cracks spread across the forecast area for most of the season and they occasionally release at random times, but during the recent cold snap glide avalanches have been releasing daily and they are located nearby many popular travel routes. These include Seattle Ridge and the motorized uptrack, Cornbiscuit, Tincan, Crow Creek area and many more. Glide avalanches are unpredictable and can randomly release even if it doesn’t look like they are currently active.

Due to the widespread distribution of glide cracks and high frequency of releases in recent days, glide avalanches are the primary hazard for travelling in the backcountry today. When glide avalanches release they take the entire snowpack with them, so in Turnagain Pass and Girdwood that means a 4-6’+ deep avalanche that is highly destructive and can runout far into valley bottoms. To avoid glide cracks we recommend carefully inspecting the slopes overhead before setting your skintrack or uptrack. Look for the classic ‘brown frown’ that indicates that the snowpack is sliding down the mountain and leaving a crevasse like crack that extends to the ground. Sometimes the ground surface in the crack is filled in with new snow, which makes identifying glide cracks a little trickier. In this case you can look for a wrinkly texture on the snow surface to indicate where buried glide cracks may exist. The best thing you can do is minimize the amount of time you spend underneath a glide crack.

See how many glide cracks you can ID on Seattle Ridge by zooming in on this photo! Photo Peter Wadsworth 12.22.23

Despite the mostly light winds over the past few days there has been enough wind transport on high elevation ridgelines to form fresh wind slabs 1-2′ deep. These will likely be localized to the highest ridges and are probably not big enough to bury a person but could easily knock you off balance in steep terrain. Look for shooting cracks and hollow, drum like snow surfaces to identify areas with recent wind slabs.

Winds are expected to increase Saturday night as a weather system enters the forecast area. If these winds pick up sooner than forecast then fresh wind slabs could start forming at upper elevations, making natural and human triggered avalanches likely. Look for signs of active wind transport along ridgelines to determine if fresh wind slabs are forming in the area you are travelling.

Prior to the last major storm a week ago there was a widespread layer of surface hoar on the snow surface. Based on field observations this week it seems like this layer was mostly destroyed by wind prior to being buried by the snowfall, but it is possible that the surface hoar was preserved in specific areas and could cause an avalanche about 2′ deep at the interface with the old snow surface. Since we have not heard of any reports of avalanches on this layer so far this week we think it is unlikely for a person to trigger. If you are venturing into a new area today you can use a compression test or extended column test to check whether the surface hoar exists in that location.

Dry loose avalanches are very likely on steep terrain today. To avoid being pushed around by loose snow make a plan to manage your sluff prior to entering steep terrain.

Wind affected snow along ridgelines could produce small wind slabs 1-2′ deep today. Photo 12.28.23