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Fri, December 9th, 2016 - 7:00AM
Sat, December 10th, 2016 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

There remains a MODERATE avalanche danger in the mountains surrounding Turnagain Pass for triggering a slab avalanche 1-2′ thick. The most suspect slopes are those that are steep, in areas less traveled and have a ‘stiff’ feel to the snow underfoot. Additionally, watch for new/old wind slabs in steep rocky terrain that could release, knocking you off your feet. On slopes that are well traveled and all areas below treeline, the danger is LOW for triggering an avalanche.  

*Ice climbers: Please let us know if you see any avalanche activity in the Portage Valley. Although natural avalanches are not expected to occur in the terrain above climbs today or into the weekend, there has been more snow and wind here than in other areas.

Special Announcements

Mark your calendar for next week’s  Fireside Chat: Avalanche Awareness and Rescue  w/CNFAIC in Girdwood!!
December 15 @ 6:30 pm – 8:00 pm FREE.  Join CNFAIC forecasters for an evening of avalanche awareness with a focus on recognizing obvious clues to instability and companion rescue.

**Planning on taking an avalanche class? The Friends of the CNFAIC is offering two avalanche scholarships through the Rob Hammel fund. Both scholarships are for $500. One is for avalanche professionals and the other is open to anyone!  The deadline for both scholarships is Dec 15th! For more information click this link  HERE.  

Fri, December 9th, 2016
Above 2,500'
2 - Moderate
Avalanche risk
1 - Low
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
  • 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

The snowpack in and around Turnagain Pass is tired, stiff and needs a good re-fresh. A little snow did fall last night, a trace in some places with 1-2″ in others. With a sunny day ahead, keep in mind that we are still concerned about a weak layer 1-2′ below the surface. This is the notorious Nov 16th buried surface hoar (image below). Although we have not seen an avalanche release in this layer for almost a week, there are many slopes away from the ‘popular’ zones that have yet to be tested. These are the areas most suspect. 

The good news is, with time triggering an avalanche becomes less and less likely. During the past couple weeks the slab above the weak layer has been ‘faceting‘ away with the cold temperatures. This process turns the slab into loose unconsolidated snow and removes it from the equation; a ‘slab’ is a necessary ingredient for a slab avalanche. The other side of the coin is where the winds have formed new slabs over the weak layer. These are the areas to be most concerned about and look for if you head into the more remote zones. To be clear, we know that most of the high traffic slopes folks have been skiing/riding avalanched weeks ago and have been filled back in, this is why those slopes are generally stable. A tricky situation when heading for fresh lines in the back bowls! 

Photo: The notorious Nov 16 buried surface hoar found in Seattle Creek drainage yesterday where an old wind slab remained. The steeper slopes above harbored loose faceted snow (no slab) as mentioned above.

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

There is a significant amount of wind affected snow out in the mountains and on our favorite slopes. Ridgelines sport wind slabs, wind crusts, scoured areas that are covered by an inch or two of fluffy new snow. That said, there are still many pockets of sheltered soft settled powder that can be found. 

Watch for fresh shallow wind drifted snow today. We saw drifts along Seattle Ridge yesterday and although they were touchy, they were too small to affect a person. In areas with more snow and wind, the slabs could be large enough to knock you off your feet. The most concerning aspect is getting on a wind slab that breaks deeper in the pack in the buried surface hoar. Older wind slabs are stubborn but a person could still pop one out on steep rocky terrain where slabs have no support from below.

Photo: Wind affected snow on Seattle Ridge.

Fri, December 9th, 2016

Mostly cloudy and obscured skies filled the region yesterday. Temperatures remain civilized and in the 20’s F at most locations. Winds were gusty from the North along the ridgelines yesterday, averaging 5-10mph with gusts to 25mph. No precipitation.

Overnight, a trace to an inch of very light snow has fallen. Ridgetop winds quieted down and were light with stronger gusts from a Northerly direction. Clouds are moving out this morning and skies are clearing with chances for more snow leaving with them.  

A ‘blocking’ high pressure will continue to dominate Alaska’s weather and clear skies with little to no chance for precipitation is forecast for the weekend and into Monday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 23   trace   0   19  
Summit Lake (1400′) 20   0   0   4  
Alyeska Mid (1700′) 24 0   0.02   11  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 21   NE    9 25  
Seattle Ridge (2400′) 23   Rimed sensors   Rimed sensors     Rimed sensors    
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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.