Turnagain Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Tue, December 6th, 2016 - 7:00AM
Wed, December 7th, 2016 - 7:00AM
Heather Thamm
Avalanche risk The Bottom Line

Today the avalanche danger is MODERATE in the alpine where trigging a fresh wind slab up to 1′ thick will be the most tender on steep leeward terrain features. Triggering a larger slab avalanche 1-2+’ thick is also possible on all aspects and the likelihood goes up as one travels to steeper slopes that have had less traffic this season. Evaluate snow and terrain carefully and manage your terrain choices with safe travel protocols.

Below 2000′ in the trees where the snow is loose and unconsolidated the avalance danger remains  LOW.

If headed to Summit Lake check out the Summit Lake Summary HERE and a recent observation from Fresno Ridge on Sunday, Dec.4, HERE.

Special Announcements

Interested in forecasting snow/weather conditions for your day in the backcountry, or your weekend trip? Join CNFAIC forecaster Wendy Wagner TONIGHT for a FREE  mountain weather talk  at Ski AK in Anchorage – 6:30-8pm!!

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.  

Tue, December 6th, 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
  • 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 Easterly ridgetop winds were transporting snow and loading Western aspects in the afternoon and overnight. With about 6-8” of snow available for transport, fresh wind slabs, up to 1ft thick could be tender today. Expect wind slabs to be extra touchy in rocky areas where the snowpack is thin and weak. This wind stiffened snow could also be adding stress to the Nov.16 layer of buried surface hoar where a slab up to 2’ thick could be enough to bury someone. Pillow-shaped snow on steep convexities and cross-loaded gullies will have more potential for this higher consequence avalanche. Today’s winds are expected to decrease this morning, but should you see activily loading snow or shooting cracks – these are obvious clues the snow is unstable.

Old ski tracks filled in quickly yesterday afternoon on a Western aspect on Tincan. Top of the ridge in this picture is 3600′. 

Avalanche Problem 2
  • 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

If you have been reading our advisories over the last few weeks then you are probably well aware of the Nov.16th layer of buried surface hoar. The most recent avalanche activity on this layer was reported on Saturday, Dec. 3rd on Cornbiscuit, where a group intentionally triggered a cornice on a steep Northern chute. They observed a slab 8-10” thick pull out and identified the buried surface hoar as the culprit. There are a number of complexities associated with this avalanche problem including the knowing the full extent of where this layer remains in the snowpack. Numerous small avalanches have occurred on this layer and numerous small snow storms keep covering up the evidence. Most of this activity has been on the popular Southwest slopes of Sunburst and Tincan and little is known about places less traveled. Don’t forget this layer is on all aspects and continues to show propagation potential in test pits above 2000’. The other important thing to note is the slab character is becoming denser with recent wind events, which means the slab could break above you once well onto the slope.  

Be sure to use safe travel protocols if venturing into avalanche terrain today: 

  • Expose one person at a time
  • Group up in safe zones
  • Have an escape route planned
  • Watch your partners and be aware of other groups around you

Check out the results of a test pit at 3300′ on a North aspect of Tincan from yesterday, Dec.5.  

Tue, December 6th, 2016

Yesterdays clear skies became overcast in the afternoon and light flurries were observed between Girdwood and Turnagain Pass. Temperatures increased throughout the day, -8F in AM to 22F by evening, along the road (1000′). Easterly ridgetop winds increased in the afternoon, 15-30mph, along ridgetops. Overnight about 2 inches of snow was recorded in Turnagain Pass and trace in Girdwood.  

Today expect scattered snow showers with an accumulation of 1-4′ inches. Temperatures will likely remain in the mid to low 20F’s and winds are expected to be light from the East.  

Dry arctic air continues to keep most of Alaska under a cold air mass including parts of Southcentral Alaska. With the exception of several low pressure systems tracking through the Gulf of Alaska bringing scattered snow showers to the area, temperatures are expected to remain cold throughout the week.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 17   2    .2 22  
Summit Lake (1400′) 14   1   .2   5  
Alyeska Mid (1700′) 19   trace   .02   10  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 13    ENE 11   35  
Seattle Ridge (2400′) 15   ESE   16   27  
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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.