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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, April 12th, 2016 - 7:00AM
Expires
Wed, April 13th, 2016 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

A  CONSIDERABLE  avalanche danger remains on all slopes under 2,500′ in elevation due to an active glide avalanche cycle. Destructive glide avalanches are occurring daily across the region.  Avoid being under the runout of glide cracks.  In addition to glide avalanches, human triggered wet loose avalanches are possible in steep terrain that harbor wet and saturated snow.

In the Alpine the avalanche danger is  MODERATE.  Human triggered wind slabs are possible on leeward slopes and cornices remain a hazard along ridgelines.  

***Travel is not recommended in avalanche terrain on the West (motorized side of Turnagain Pass).

If you are headed to the Summit Lake area don’t forget to check  Summit Lake Summary.    

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Tue, April 12th, 2016
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
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
Considerable (3)
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
  • 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

Glide avalanches remain our primary concern as they continue to release in areas we recreate. The most concerning zone is Seattle Ridge and the popular motorized up-track. This well traveled slope is hanging in the balance (pictured below). Although much of the snowpack has already avalanched along Seattle Ridge, there is still more to come… Due to the dangerous and destructive power of even a small glide avalanche, we are recommending that people do not travel in avalanche terrain (including runout zones) on the motorized side of Turnagain Pass (West Side). Glide avalanche hazard also exists on the non-motorized slide of Turnagain Pass. Travel underneath existing glide cracks is not recommended. In addition, be on the lookout for new glide cracks forming. 

New glide avalanche activity (from the past 24-hours) includes Max’s South face, and two on Easterly facing slopes in the Summit Lake area. 

Photo: Max’s Southerly face – this glide released mid-slope and you can see a crack to the looker’s left that is prime to release:

 

Photo: Summit Lake fresh glide avalanche. There is little snow on these slopes but they still clearly pose a threat!

 

Seattle Ridge Glide Activity:
Although visibility was poor yesterday it looks as though no new glide avalanches occurred. We should be able to see these as they create such brown streaks and dirty debris piles. However, there may have been new wet snow avalanches considering it was difficult to see white(ish) debris.

Photo: Repeat Offender slide path with older glide avalanches running over the lower part of the up-track and cracks threatening rest of the up-track:

 

Seattle Ridge glide older glide activity seen across from the motorized lot:

Avalanche Problem 2
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

As temperatures rise today watch for any superficial re-freeze of the snow surface to soften; if the sun pokes through this will speed up the process dramatically. How much re-freeze occurred last night is tough to tell as the cloud cover was in and out (clear skies overnight can re-freeze the surface even in temperatures are as warm as 40F….due to longwave radiation loss). If you find yourself on a steep slope with saturated wet snow then triggering a wet loose avalanche, or push-a-lanche, in steep terrain will be possible.

Additional Concern
  • 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

At the uppermost elevations, where dry snow exists, watch for lingering wind slabs on steep leeward slopes. These areas are in the 3,500′ range and higher. Also, cornices could start falling any day now with these warm temperatures and limiting time under them as well as giving them a wide berth is recommended.

Weather
Tue, April 12th, 2016

Partly cloudy to obscured skies filled the region yesterday. Light precipitation fell along Turnagain Pass adding up to 2″ of new snow above 2,500′ and .2″ of rain below. Ridgetop winds were averaging in the 10-15mph range with gusts to 40mph from the East at the Sunburst weather station.

Today, we should see clouds move in with a chance for breaks in cloud cover here and there through the day. No precipitation is expected and temperatures are slated to be warm…..up to 45F at 1,000′ and 35F on the ridgetops. Ridgetop winds are expected to be ~10mph from a generally Easterly direction.

Looking forward to Wednesday and later this week, we remain in an unsettled weather pattern as a series of low-pressure systems spin to our South in the Gulf shooting moisture our way.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 34   1   0.2   115  
Summit Lake (1400′) 36   0   0   32  
Alyeska Mid (1700′) 36   0   0   101  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24   NE   15   46  
Seattle Ridge (2400′) 30   SE   12   30  
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Riding Areas
Updated Wed, December 11th, 2019

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
Closed.
Placer River
Closed
Closed.
Skookum Drainage
Closed
Closed.
Turnagain Pass
Closed
Closed.
Twentymile
Closed
Closed.
Seward District
Carter Lake
Closed
Closed.
Lost Lake Trail
Closed
Closed.
Primrose Trail
Closed
Closed.
Resurrection Pass Trail
Closed
Closed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor
Closed
Closed.
South Fork Snow River Corridor
Closed
Closed.
Summit Lake
Closed
Closed.

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