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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
Thu, December 11th, 2014 - 7:00AM
Expires
Fri, December 12th, 2014 - 7:00AM
Forecaster
John Fitzgerald
The Bottom Line

The avalanche danger is mainly LOW in the alpine, with isolated pockets of MODERATE danger.   In steep starting zones above 3,000′, the possibility exists for triggering old wind slabs up to 18 € in depth.   These slabs will be difficult to trigger but hold some potential to propagate across slopes.   Giving the snowpack another day to adjust to the most recent load by sticking to slopes 35 degrees or less will be your best bet.

At treeline, in the mid elevations (1,500′-2,500′), a rain crust caps the surface and has locked the snow into place.   The avalanche danger is LOW in this elevation band today.

Below treeline (1,500 and lower) there is not enough snow cover for avalanches to be of concern.

Early season hazards such as rocks, stumps and open water pose the greatest potential for harm.   A slick and impermeable rain crust between 1,500-2,500′ in elevation will also require careful travel.

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Thu, December 11th, 2014
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
No Rating (0)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Yesterday my partner and I found generally stable snow in the higher elevations.  We found evidence of extensive avalanche activity that had occurred during and immediately after the most recent storm on Tuesday Dec 9th.  Looking under the snow surface showed us mostly strong snow with one exception.  We were able to see some propagation potential along a weak layer 18″ below the surface.  Because of this result and only minimal information since the storm, it will be wise to treat steep upper elevation slopes with a healthy dose of respect.  While the weak layer in question in our snowpit is one that typically stabilizes quickly, I’m not ready to jump into this type of terrain without gathering more information from below the surface.  The general trend today will continue to be towards better stability.  The likelihood of triggering an avalanche is on the low end of the scale, BUT there are stiff older wind slabs that are sitting on weaker snow.  These older wind slabs will be difficult to recognize, as they are blanketed by low density powder.

Venturing into steeper terrain in the upper elevations will require advanced snowpack assessment skills and the ability to detect old wind slabs hiding underneath 8-10″ of light powder.  You can also hedge your bets by sticking to terrain 35 degrees or less in the alpine today.

As mentioned above, early season hazards and a stout & slick rain crust in the mid elevations are legitimate concerns and require careful travel in order to avoid injury.

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Yesterday we observed one glide avalanche on the East face of Pyramid that had moved 10-20 feet downhill over the past day.  While glide avalanches are not a widespread issue currently, it is worth keeping them in mind.  Both Eddies and Tincan have numerous older glide cracks that have not moved over the past couple of weeks.  The nature of glide avalanches makes it very difficult to know when they might release.  With this in mind, it is best to steer clear of glide cracks and to keep track of where they are.

Weather
Thu, December 11th, 2014

Earlier this week rain, snow, warm temps and moderate winds created unstable conditions throughout the area.   Since Tuesday Dec 9th, the weather has quieted down and allowed the snowpack to adjust.  

Temperatures over the last 24 hours have cooled into the low 20s F.   Ridgetop winds have been light and there has been no new precipitation.

Today expect a continuation of this quiet weather.   Skies will be mostly clear with some fog in the valleys.   Temperatures will be in the low 30s F at 1,000′ and in the mid 20s F at ridgetop levels.   Winds will be light out of the North at 5-15 mph.   No new precipitation will fall today.

The extended outlook is showing a chance for snow and possibly rain at the lower elevations as we head into the weekend.

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 29  0  0 18
Summit Lake (1400′) 22  0  0  4
Alyeska Mid (1700′) 29  0  0  11.8

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  25  WNW  6  18
Seattle Ridge (2400′)  28  var  8  23
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Riding Areas
Updated Mon, October 26th, 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
Twentymile
Closed
Seward District
Carter Lake
Closed
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Snug Harbor
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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.