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Wed, February 17th, 2016 - 7:00AM
Thu, February 18th, 2016 - 7:00AM
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

The avalanche danger remains  MODERATE  today in the Alpine (above 2500′) where lingering wind slabs 1-3′ deep may prove reactive in steep terrain greater than 35 degrees. Skiers/snowmachiners, direct sun or cornice fall are all likely triggers, particularly later in the day when daytime temperatures peak.  

In the Treeline elevation band (1,000′ €“ 2500′) the danger is also  MODERATE,  where the potential for glide avalanches continues to be an issue.  

Special Announcements

Do you frequent Hatcher Pass? Mark your calendars!

TONIGHT!  – FREE Avalanche Awareness Class hosted by Hatcher Pass Avalanche Center in partnership with F-CNFAIC and the Hatcher Pass Mountaineering Huts Group. Join CNFAIC Avalanche Specialist Aleph Johnston-Bloom at the Palmer High School Library from 6:30-8pm.  

Saturday, February 20th  Hatcher Pass Avalanche Center is having their annual fundraiser at Gov’t Peak Chalet near Hatcher Pass. This event will feature a slide show by local climber and ski mountaineer, Kirsten Kremer,  a Silent Auction, Live Music and FUN!  Click  HERE  for more info on both events.

Wed, February 17th, 2016
Above 2,500'
2 - Moderate
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
0 - No Rating
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
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

Lingering wind and storm slabs will still be possible to trigger in steep (>35 degree), wind-loaded terrain. Observations yesterday identified a weak interface in the snowpack at the boundary of the most recent storm and the snow surface it landed on, approximately 15-20″ below the surface. Preserved precipitation particles remain sandwiched between stiffer snow layers above and below and were still reactive in stability tests. We suspect this structure combined with rapid warming and sunshine were reason the skier triggered wind slab avalanches in Goldpan area occurred on Monday and what the cornice triggered slab avalanches are running on as well. Avalanching has not been widespread and in general the snowpack has shown good bonding. However, this particular set-up needs to be considered, especially later in the day. In the Girdwood Valley, a thin rain crust was observed up to 3100′ as the bed surface of wind/storm slabs that released during avalanche mitigation.

We have reached the time in Alaska where sun is a now a factor. ‘It feels like spring’ has been the general sentiment. Pay attention to increased solar input, warm ambient temperatures and changing surface conditions in the terrain you are traveling through. Warming may make slabs easier to trigger with the weight of a skier or snowmachine. Increased rollerball activity is a good indicator of the snowpack heating up rapidly and a sign that the surface is weakening. Avoid steep (>35 degrees), leeward slopes (South and West) late in the afternoon when the sun is at its strongest. 

Loose snow avalanches: There is the potential for wet loose avalanches on steep southerly slopes and dry loose avalanches on steep northerly slopes. Remember these will release at your feet but may gain momentum and catch you from behind as you travel downhill.  Avoid being knocked off your feet in steep high consequence terrain. 

Another look at at the skier triggered avalanches in Goldpan on 2/15.


Avalanche Problem 2
  • Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Yesterday we were able to get a closer look at the cornice fall on the South side of Magnum. It ran all the way to the drainage below and had pulled pockets of slab out with it. It covered the region where the skin track often goes. There were a number of reports from the advisory area of other large cornice falls that triggered the slopes below. Cornices will continue to be tender and travel on or below should be avoided. Remember they can break farther back than expected. Warming temperatures in the afternoon and direct sunshine may increase the hazard for both natural and human triggered cornice fall. 

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

The glide avalanche problem continues. We observed two recent releases yesterday and glide cracks grow daily. All that needs to be said is avoid travel underneath glide cracks.



 Glide avalanche on Seattle Ridge.

Wed, February 17th, 2016

Yesterday was mostly clear with periods of valley fog. Temperatures were in the low 20Fs to mid 30Fs. Winds were light and variable. Skies were mostly clear overnight.  

Today will be mostly sunny with a chance of valley fog. This afternoon may become partly cloudy. Temperatures will be in the mid 20Fs to mid 30Fs and winds will be Easterly 15-25 mph.

Tonight will be partly cloudy with another day of sunshine on tap for tomorrow as we sit under a ridge of high pressure for a couple days.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 24    0 0   103  
Summit Lake (1400′) 22  0 0 30  
Alyeska Mid (1700′) 25  0 0 85

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  22 variable   7   19  
Seattle Ridge (2400′)  28  n/a n/a   n/a  
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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.