Seattle Ridge slab avalanche 11.26.21. Photo from anonymous
Tincan Common slab avalanche 11.26.21. Photo from Matt Dietrick
Hope area avalanches, an old windslab over a persistent weak layer from 11.26.21. Photo from anonymous
Photo 11.26.21, exact release date unknown
|Signal Word||Size (D scale)||Simple Descriptor|
|Small||1||Unlikely to bury a person|
|Large||2||Can bury a person|
|Very Large||3||Can destroy a house|
|Historic||4 & 5||Can destroy part or all of a village|
Our primary concern today is persistent slab avalanches which could be triggered on a variety of weak layers (details here and here) that are becoming more active as the 20-34” of very light new snow from this week gradually settles into a more cohesive slab. These slabs can be 2-3′ deep and have the potential to propagate across an entire slope. Triggering an avalanche is more likely in areas where the wind has transported snow to create a firmer slab. The most recent pulse of snow came in on Wednesday (~10-12″) with no wind, which makes it very hard to see where the prior storm snow has been redistributed by wind. Assessing the slab character of each slope by travelling off trail and looking for red flags, such as collapsing (whumphing) and shooting cracks, is important to evaluate conditions today.
We recommend keeping a conservative mindset today because of the weak snowpack structure and a high level of uncertainty about where conditions are unstable. Persistent slabs can be tricky because it is not always the first person on the slope who triggers an avalanche. We have observed remote triggering in avalanches yesterday and expect similar conditions to remain throughout the weekend. If you want to keep it safe today, stay on terrain with less than 35 degree slope angle and pay attention to steeper slopes above you. It is important to travel one at a time in terrain above 30 degree slope angle and spot your partners to minimize the consequences if an avalanche is triggered.
Shooting cracks in new snow over faceted weak layer from 11.25.21 on Seattle Ridge
Snowpack summary from Sunburst on 11.26.21
Summit Lake Area – An avalanche reported in the Hope area yesterday seems to line up with conditions observed in Summit Lake recently. This avalanche was a hard wind slab over faceted snow that released along a ridgeline. Even though this is outside our forecast zone it is worth noting if you are planning to travel in Summit Lake today, where the new snow from this week only added up to 3-6” but old wind slabs could continue to be a problem.
Glide avalanche activity has slowed down in the past week, but we observed a release on the south face of Lipps sometime in the past few days. This is a reminder the glides are still active in our area. It is key to minimize time underneath glide cracks as they can produce very large and unsurvivable avalanches. They can also be a hazard to fall into on skis or snowmachines and are harder to see in many locations because of the recent light storm snow.
Yesterday: Temps in the single digits with winds less than 5 mph out of the west and gusts below 10 mph. Trace amounts of precipitation. Mostly cloudy with variable cloud layers throughout the day.
Today: Temps in the negative single digits with light northwest winds at 5-10 mph and gusts up to 15 mph. Partly to mostly cloudy throughout the day. Snow showers are possible with accumulation of less than an inch.
Tomorrow: Sunday looks like more cold temps and calm winds with scattered clouds. The next wave of precipitation should arrive during the day on Monday with a low pressure system moving into the area.
PRECIPITATION 24-hour data (6am – 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880′)||6||N/A||0.2*||64|
|Summit Lake (1400′)||4||0||0||11*|
|Alyeska Mid (1700′)||6||N/A||0.02*||N/A|
* Precipitation sensors are struggling to accurately capture the snowfall totals from the past few days.
RIDGETOP 24-hour data (6am – 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
|Seattle Ridge (2400′)||1||NNE||3||8|
|05/11/22||Turnagain||Avalanche: Cornbiscuit and Magnum west faces||CNFAIC Staff Forecaster|
|05/07/22||Turnagain||Observation: Granddaddy||Kit Barton|
|04/29/22||Turnagain||Observation: Sunburst wx station||AS/ MM/ AM/ NH|
|04/28/22||Turnagain||Observation: More Turnagain Pass/Summit Lake wet slab activity||Alex Marienthal|
|04/27/22||Turnagain||Observation: Magnum||Sykes / Buttrick Forecaster|
|04/27/22||Turnagain||Observation: Girdwood/Summit/Turnagain Road obs||A S|
|04/24/22||Turnagain||Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path||CNFAIC Staff Forecaster|
|04/24/22||Turnagain||Avalanche: Seattle Ridge uptrack||Martin Schmidt|
|04/24/22||Turnagain||Observation: Pastoral||Jason Konigsberg|
|04/24/22||Turnagain||Observation: Sunburst||Lance breeding|
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: firstname.lastname@example.org
|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.