The potential for skiers, riders and snowmachiners to trigger avalanches within layers of the new snow is very high today. Terrain above treeline harbors large areas of slab, including wind slabs, that will be very sensitive to human triggers. The steady and often rapid loading of this week has created unstable conditions in the upper layers of the snowpack. Those of you who have ventured out into the mountains this week have witnessed this firsthand, getting machines stuck in the weak snow and enduring arduous trail breaking. This new snow is dense and unsupported in many areas, making travel slow and challenging. Below 1000 feet we have wet snow due to rain falling over the past 24 hours. It all boils down to the fact that we have a lot of new snow sitting on multiple weak layers. While we have limited info from the upper elevations, we know that the snow is very unstable, as both AKDOT & Alyeska resort have been able to trigger avalanches on a variety of aspects and elevations. Large natural avalanches as recent as yesterday morning have been observed in the region. The recent observations from the backcountry that we do have paint the picture of instability well.
While deep slabs are a secondary concern to storm snow/wind slabs, do not underestimate the potential destructive force of this type of problem. Large, dense slabs that have formed over the past four days sit on a base of weak snow. Triggering avalanches that break into these deeper layers could have dire consequences. If caught in a deep slab avalanche, the chances of surviving are low. I like to think of this problem as one that is unmanageable. As such, it is important to keep terrain choices very conservative. An avalanche triggered even in seemingly “small” terrain could have serious consequences given the large volume of snow. While storm snow instabilities will diminish within days of the end of a storm, this deep slab problem will be with us for an extended period of time.
The Turnagain Pass area has received ~7 inches of new snow with .6 inches of water in the past 24 hrs., bringing our storm period totals to over 50 inches. Yesterday morning winds diminished to an average of 20 mph out of the East. Temperatures have been mild, hovering in the low 20s on ridgetops and low 30s at 1000 feet. Rain was falling yesterday below 1,000 feet.
Today will bring lingering snow showers to the area with accumulations of up to 3 inches of snow during the day. Temperatures will remain just below freezing at 1000 feet and winds will be out of the East and Southeast at 20-30 mph.
Snowfall and winds will increase in intensity this evening and into tomorrow. We should expect to see this generally moist weather pattern to continue over the next several days.
Kevin will issue the next advisory Saturday morning December 29th.
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer Forecaster|
|04/12/21||Turnagain||Observation: Tincan||Johnston-Bloom / Latosuo Forecaster|
|04/10/21||Turnagain||Observation: north sides||lance breeding|
|04/09/21||Turnagain||Observation: Girdwood to Turnagain Road Observations||W Wagner Forecaster|
|04/05/21||Turnagain||Avalanche: Resort bowl Seattle creek head wall||Clint Kyffin|
|04/04/21||Turnagain||Observation: Center Ridge||Andy Moderow|
|04/03/21||Turnagain||Observation: Repeat Offender – Seattle Ridge||Troy Tempel|
|04/02/21||Turnagain||Observation: Seattle Ridge||Wagner / Schauer Forecaster|
|04/01/21||Turnagain||Observation: Pete’s||Schauer/ Cullen Forecaster|
|03/31/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: email@example.com
|Area||Status||Weather & Riding Conditions|
This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.