Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sun, November 27th, 2016 - 7:00AM
Expires
Mon, November 28th, 2016 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

The avalanche danger is  MODERATE  in both the alpine and at treeline on all aspects due to a widespread layer of buried surface hoar. Human triggered slab avalanches 1-2 feet thick are possible today and will have higher consiquences on larger slopes. Also triggering an isolated windslab up to 6″ thick is possible on steep features near ridgetops. Be extra cautious choosing your route and don’t hang out under glide cracks.  

***Observations from the Summit Lake area on the Kenai are showing a similar snowpack. Weekly summaries will begin on December 2nd.

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Sun, November 27th, 2016
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
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
Moderate (2)
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
  • 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

Over the last week the alarms have sounded due to a widespread layer of buried surface hoar sitting below 1-2 feet of snow. Observers continue to find this layer on all aspects and elevations throughout Turnagain Pass. Up until a few days ago human triggered and remote triggered avalanches were happening daily with a couple dozen avalanches reported over a 7-day period. These avalanches have been small to medium in size; just large enough to bury a person or seriously injure you in a ride. With time this layer has been adjusting to its load and becoming less reactive and harder to trigger.  Last nights snowfall, about 4 inches, arrived after winds calmed down and was just enough to cover up recent avalanche activity. Don’t forget buried surface hoar is a persistent weak layer and human triggered avalanche are still possible. This layer has not gone away and should be a major factor in slope choice today. Larger and/or steeper, more wind-loaded slopes that haven’t been ridden still have the potential to avalanche and could fracture once well onto the slope. Be aware of the consequences below you and keep an eye out for recent wind loading, shooting cracks and whumphing sounds.  Practice safe travel techniques like regrouping in safe zones and only expose one person at a time in avalanche terrain. This can be challanging to practice in crowded areas, thus be extra aware of other groups who may be traveling above or below you.

 

A view of avalanche activity on the popular Sunburst SW face. Photo taken Novemeber 24th before new snow from last night covered it up.  

Avalanche Problem 2
  • 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 numerous shooting cracks were observed near Taylor Pass and Sunburst Weather Station, where moderate winds were activily loading Western aspects. Triggering a small wind slab up to 6” thick is possible in steep leeward terrain near ridgetops. Be aware of supportable and hollow sounding snow hidden below the four inches of new snow that fell overnight. Avoid steep slopes if you experience shooting cracks.

 

Several 10-20′ shooting cracks were observed yesterday near Taylor Pass

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

Several glide avalanches have released this week including one observed yesterday morning on the West face of Pyramid. Several glide cracks have been noted in popular terrain like Tincan’s Common bowl and the SW face of Sunburst. If you see glide cracks give these a wide berth, minimize time spent underneath, and remember these are totally unpredictable. They are not triggered by humans and are the entire snowpack releasing. 

Weather
Sun, November 27th, 2016

Yesterday morning about an inch of new snow dusted Turnagain Pass and a trace was noted in Girdwood. Skies were overcast becoming obscured in the afternoon.   Easterly ridgetop winds were moderate (15-25mph) becoming light by the evening. Temperatures were on the rise all day, teens F to mid 20F’s.  

Overnight 4 inches of new snow fell in Turnagain Pass and only an inch in Girdwood. Temperatures remained just below freezing and winds were light from the Northeast.  

There is a chance for a few more inches of snow today. Ridgetop winds are expected to remain light and variable and temperatures should be in the mid 20F’s.  

Cooler temperatures and clear skies are expected tomorrow evening through Wednesday with another chance for snow near the end of the week.

***Sunburst Weather Station has not recording weather data since Nov.25th. We are currently assessing and hope to get it repaired soon.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 24   4   .4   20  
Summit Lake (1400′) 23   trace   .1   2  
Alyeska Mid (1700′) 26   1   .11   4  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  n/a*** n/a*** n/a*** n/a***
Seattle Ridge (2400′) 21   SE/variable   9   26  
Observations
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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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