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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sat, January 7th, 2017 - 7:00AM
Expires
Sun, January 8th, 2017 - 7:00AM
Forecaster
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

A  MODERATE  avalanche danger remains in the Alpine where triggering an isolated wind slab or a deeper hard slab 2+’ thick is possible on steep wind loaded slopes that haven’t avalanched. At Treeline and below there is  LOW  avalanche danger, where triggering an avalanche is unlikely, but not impossible.  

In the periphery zones of Girdwood, Johnson Pass and Summit Lake a shallower snowpack exists and it may be easier to trigger a slab avalanche in these areas.  

Check out the Summit Lake Summary  HERE.

*** If heading to Hatcher this weekend – unstable conditions exist – check the Hatcher Pass advisory  HERE!    Mark your calendars for the FREE rescue workshop at Hatcher Pass on January 14th. More info  HERE.  

Special Announcements

UPCOMING EVENTS:

  • Today at 10:30am join CNFAIC and AMDS at the Turnagain Pass motorized lot for a “passing off” of the keys celebration (keys to a brand new 2017 Ski Doo Summit SP 850)! HUGE thanks to AMDS and BRP/Ski Doo for granting the Friends of the CNFAIC a new loaner snowmachine for the season!! Stick around for a quick state of the snowpack discussion after!
  • Sunday, January 8th at 5:30 pm,  Kenai Peninsula Avalanche Information Workshop at the  Flats Bistro.  Hope to see you there! More info  HERE.
  • Tuesday January 10th, Discussion on Backcountry RESCUE presented by team members of the U.S. Air Force 212th Rescue Squadron (RQS/PJ’s) and Alaska Mountain Rescue Group (AMRG). Details  HERE!

*Its that time of year again, PFD time! If you are feeling generous and want to support your local avalanche center, Pick Click Give, makes it really easy to become a supporting member of CNFAIC.

Sat, January 7th, 2017
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
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

This weekend if choosing to travel in avalanche terrain it is important to remember although the snowpack is wind hardened and tired, it does have a poor structure. There are a variety of weak layers (buried surface hoar and facets) in the middle of the pack as well as at the bottom (facets). The slab on these weak layers is quite variable and hard – and though difficult to trigger, the possibility does exist. Steep wind loaded slopes (Northern and Eastern) that haven’t avalanched yet are the most suspect. Likely trigger spots are in thinner areas near rocks. Obvious signs like cracking and ‘whumpfing’ are becoming less common, making it more difficult to assess slope stability. Watch for areas with hard over soft snow and hollow sounding snow. Avoid cornices, wind pillowed snow in start zones and loaded areas farther down slope (from the strong winds). Hard slabs may allow you to get well out onto them before breaking. Heavier loads, such as multiple snowmachines or people on the slope at one time might tip the balance. Safe travel protocol is your friend. Remember to only expose one person at a time, watch your partners, have an escape route planned, group up in safe zones and pay attention to other groups around you. 

In the periphery areas (Girdwood, Johnson/Lynx Creek and Summit Lake) where a thinner snowpack exists, several observers have experienced collapsing/whumpfing in more recently which indicates the potential for these persistent slab avalanches may be higher. Heighten caution is advised if traveling out of the core Turnagain Pass terrain. 

Slab over facets on the North side of Tincan Wednesday. Photo: Heather Thamm

 

 

Avalanche Problem 2
  • 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

Believe it or not, 3 glide avalanches have occurred in the past week in the Turnagain Pass zone. These are SE aspect of Lynx CreekSE aspect of Seattle Creek, and the SW face of Eddies. Along with recognizing wind affected snow, keep an eye out for glide cracks and limit time under these. 

 

Weather
Sat, January 7th, 2017

Yesterday was clear, sunny and cold. Temperatures were in the teens along ridge tops and single digits in the valleys. Winds were light and Northerly. Overnight temperatures were near 0F and below, skies were clear and winds remained light.

Today, tonight and tomorrow will be similar as blocking pattern (Omega block) dominates the weather in Southcentral Alaska into next weekend. Daytime temperatures will be slightly warmer in the teens-20Fs and dip back down to single digits at night. N winds will be mostly light with some gusts into the 20s. Skies will be mostly clear.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  5  0  0 35  
Summit Lake (1400′)  2   0    0 11  
Alyeska Mid (1700′)  10  0  0 23

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  10 NE 5   18
Seattle Ridge (2400′)  13 WNW   7   15
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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.