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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, April 13th, 2016 - 7:00AM
Expires
Thu, April 14th, 2016 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

Below 2500′ the avalanche danger is  CONSIDERABLE  today due to a continued pattern of warm temperatures and an active glide avalanche cycle. Natural wet loose avalanches in steep terrain are possible and human triggered wet loose avalanches are likely.  Avoid being under the runout of glide cracks and travel on or under cornices.

In the Alpine the avalanche danger is  MODERATE.  Human triggered wind slabs are possible on steep leeward slopes and cornices are also a concern for this elevation band 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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Wed, April 13th, 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

New glide activity was observed yesterday and continues to be the primary concern due the destructive and unpredictable nature of the releases. Travel underneath existing glide cracks is a total gamble. The zone above and around the popular motorized up-track on Seattle Ridge continues to have our hackles up. 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 a lot of snow that could release. There was no overnight freeze in the 1000-2500′ elevation band and there is the possibility of rain today. These weather factors may increase glide activity.

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. 

An example of new glide avalanche activity (from the past 24-hours). photo: Tim Glasset 

Looking towards the uptrack and noting the amount of snow that still could slide. 

 

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

Yesterday the temperatures rose above freezing in the Alpine and the sun was shining. The new snow got progressively wetter throughout the day. There was some minor natural roller ball activity and some natural wet loose activity on steep slopes. Low elevations were very punchy and saturated in the afternoon. There was no overnight freeze from 1000′- 2500′. This combined with the possibility of rain will up the likelihood and potential for natural and human triggered wet loose avalanches today. Any periods of sunshine will also be a factor. Remember wet loose avalanches can be hard to escape once initiated and particularly hazardous if they push you into a terrain trap.

Natural wet loose avalanche on Seattle Ridge that occurred in the afternoon yesterday. 

 

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

Yesterday it was evident that the wind had redistributed the new snow and there were deeper pockets of snow along leeward ridgelines. We have limited information from the Alpine but traveling to 3200′ showed a structure that could be triggered on steep wind loaded slopes. Wind effected storm snow sits on top of a stout melt-freeze crust. Watch for cracking while traveling and recognize that this set-up could be sensitive on unsupported features. 

Cornices: We have been wondering when we will see a natural cornice fall cycle. So far they been “hanging in there” but yesterday we observed two cornice falls and the avalanches that were triggered by them in Portage Valley. These were both in terrain at or below 2500′. This is similar to the corniced ridgeline elevations in the Seattle Creek drainage. Continued warm temperatures may increase the likelihood that these will fail. As always, avoid travel on or under cornices at any elevation and remember that they may break farther back than expected. 

Weather
Wed, April 13th, 2016

Yesterday was mostly sunny with some high clouds. Sky cover trended to overcast by the evening. Winds were light and variable. Temperatures were warm, averaging in the high 40Fs at 1000′ and the high 30Fs at 3000′. Center Ridge Snotel hit 50F at 4 pm and Sunburst Wx station saw 34F at 3 pm.  

Today will be partly to mostly cloudy with a chance of rain in the afternoon. The temperatures will remain warm and above freezing above 3000′. Wind will be light and easterly.  

The trend for the week is forecasted to be scattered showers and above average temperatures as the general pattern stays the same.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 41    0 0   114
Summit Lake (1400′)  40 0   0   31  
Alyeska Mid (1700′)  38  0 0   99  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 32   variable   5    33
Seattle Ridge (2400′)  34  variable  3 18  
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Riding Areas
Updated Mon, December 02nd, 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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