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Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, November 20th, 2012 - 7:00AM
Expires
Wed, November 21st, 2012 - 7:00AM
Forecaster
Kevin Wright
The Bottom Line

Welcome to the new website layout!   We are joining a nationwide trend to give the forest service avalanche centers a similar look and provide information in a consistent manner. The content only has minor changes from last season, but we think you will like the new web interface. Let us know your thoughts.

We are issuing advisories 5 days a week through November on Sat, Sun, Tue, Thur, Fri. The next advisory will be Thursday November 22nd.

Bottom Line

With little change in the weather and persistent cold temperatures, the avalanche issues we’ve had over the last week are not changing very quickly.  Reports of easily triggered avalanches in the alpine zones above 3000 feet over the last 2 weeks are keeping us on our toes.  The thin snow cover in the mountains right now is a good limiting factor that should encourage staying in safer zones.  Steeper slopes greater than 35 degrees above treeline should be avoided altogether.

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Tue, November 20th, 2012
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

Rotten snow can be found nearly everywhere right now, and in some cases those weak facets will collapse when stressed.  The recipe that caused the recent skier triggered avalanches is relatively simple to understand.  All the October snow sat around during cold temperatures and turned to sugary facets before it got buried by subsequent storms.  Shallow, weak snow is easily triggered by the weight of a person.  If you are interested in investigating snow pits, now is a great time to look at textbook instability.  Which makes it a bad time to explore farther into the backcountry.  

On our backcountry patrols we’ve been quite conservative in our route and slope choices.  Skiing “lightly” to avoid hitting submerged rocks, and avoiding the steeper slopes is a good idea until our situation changes.  Examples of recent avalanches can be found HERE and HERE.

Sunburst crown detail

Besides the bulls-eye information of skier triggered avalanches, our pit tests are showing a collapsible weak layer and a tendency to propagate.  Most stability tests are showing low to moderate strength, and will propagate across an extended column when the underlying weak layer collapses.  This is very pertinent information!  When a professional guide sees evidence like this, he/she will very deliberately alter travel plans to stay on conservative lower angle terrain.  

The nature of avalanches breaking to the ground in our shallow snow situation is another good reason to stay conservative.  Taking a ride through the rocks increases the chance of major injury.

Lower elevation slopes below treeline are more stable than up high due to a slightly better snowpack structure.  Shallow snow cover in the trees will make travel challenging however, until we get more snow.  

Weather
Tue, November 20th, 2012

It’s been mostly clear and cold over the last couple days.  Minimal precipitation has not contributed much to the avalanche equation.  The jet stream pattern is bringing colder arctic air across Alaska and currently diverting most of the Pacific moisture to Washington and British Columbia.  Light wind and a strong temperature inversion is happening this morning between Girdwood and Summit.  The outlook for a pattern change doesn’t look good until sometime next week.  Don’t expect much precipitation in the next few days.  The cold temperatures and shallow snow are forming a strong temperature gradient that continues to weaken the snow we already have on the ground…


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).  

I will issue the next advisory on Thanksgiving morning, Thursday November 22nd.  

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Riding Areas
Updated Fri, May 01st, 2020

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: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Placer River
Closed
Skookum Drainage
Closed
Turnagain Pass
Closed
Closed as of May 1. Thanks for a fun, safe season!
Twentymile
Closed
Seward District
Carter Lake
Closed
Lost Lake Trail
Closed
Primrose Trail
Closed
Resurrection Pass Trail
Closed
Snug Harbor
Closed
South Fork Snow River Corridor
Closed
Summit Lake
Closed

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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.