Last night we got reports of an avalanche on Repeat Offender, the site of the large fatal avalanche in 1999. A group of snowmachiners had just started descending the standard trail from Seattle ridge when it released remotely 100 yards away. Initial reports estimate the size as 600-1200 feet wide. It undoubtedly took the entire depth of the snowpack, breaking on old October and November weak layers. Reports say that Main Bowl also slid on the west side of the ridge.
The deep slab problem is difficult to understand because it won’t show signs of instability until it avalanches in a big way. You also won’t see a lot of slopes avalanching on the same day, meaning that the mountains will look good and enticing. The problem is that when you find a trigger point, the resulting slide will be much bigger than you want. This is a low frequency, but very high consequence problem that is difficult to predict.
We have compiled ample evidence to show that the mountains are ripe for this to happen again. Over 10 feet of new snow in the last 2 weeks has already brought down a number of large avalanches including at Tincan, Seattle ridge, Johnson Pass, Portage, and elsewhere. This is the most dangerous persistent deep slab problem we’ve had in our region in a number of years. The only way to avoid becoming a statistic is to alter our behavior and choose conservative, lower angle terrain.
Yesterday we found a small reactive wind slab in the top 6 inches of surface snow at treeline. Wind deposit areas may have this layer of stiffer, less stable snow. Compared to the deep slab issue, this is a relatively minor and manageable problem.
A few inches of colder snow fell yesterday with light wind in the mountains. Today is likely to be the first day since December 22nd without any snowfall. Expect sunny skies and light wind in the mountains with slightly colder temperatures.
The clear weather will give way to another weak storm tonight, with snow expected again tomorrow and a return to warm and moist flow by the weekend.
|04/21/21||Turnagain||Observation: Sunburst||Schauer/ Behney Forecaster|
|04/19/21||Turnagain||Avalanche: Triangle, Seattle creek||Will Morrison|
|04/18/21||Turnagain||Avalanche: Turnagain Pass Road Obs||Andy Moderow|
|04/18/21||Turnagain||Observation: Seattle Ridge, approximately 300 yards south of the up track||Brent Byrne|
|04/17/21||Turnagain||Avalanche: Road obs||Johnston-Bloom / Moderow Forecaster|
|04/16/21||Turnagain||Avalanche: Seattle Ridge||Wendy Wagner Forecaster|
|04/16/21||Turnagain||Avalanche: Turnagain Pass, non-motorized side seen from Seattle Ridge||CNFAIC Staff Forecaster|
|04/16/21||Turnagain||Observation: Sunburst||Lance breeding|
|04/15/21||Turnagain||Observation: Tincan||Schauer/ Rothman Forecaster|
|04/13/21||Turnagain||Observation: Turnagain Pass Road Obs||A Schauer 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.