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ARCHIVED - Forecasts expire after 24 hours.
Issued
Wed, January 11th, 2017 - 7:00AM
Expires
Thu, January 12th, 2017 - 7:00AM
Forecaster
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

There is a generally  LOW  avalanche danger in the mountains surrounding Turnagain Pass. Although triggering a slab avalanche is unlikely, old hard wind slabs 1-3′ thick sitting on faceted snow remain. With the right trigger spot and/or the right amount of force (several people and/or snowmachines) it may not be impossible to get a slab to pop out. Most suspect areas are unsupported slopes in steep rocky terrain.    Additionally, watch for glide cracks and glide avalanches, as these may be active this week.

Special Announcements

Join us tomorrow night, Thursday January 12th, 6:30pm, for a FREE basic avalanche awareness and discussion by  CNFAIC on the current snowpack in Turnagain Pass  at the Alaska Avalanche School, Details  HERE.  

* Hatcher Pass continues to have  unstable conditions,  check the Hatcher Pass advisory  HERE  if you are thinking of heading this way. Also – mark your calendars for the  FREE rescue workshop at Hatcher Pass on January 14th.  More info  HERE.  

Wed, January 11th, 2017
Alpine
Above 2,500'
1 - Low
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
  • Normal Caution
    Normal Caution
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
More info at Avalanche.org

High pressure continues to dominate our weather pattern and not much is expected to change today with the exception of temperatures cooling throughout the day. The inversion is forecasted to break down as cold air pushes into the region.

It is always important to keep in mind that LOW avalanche hazard does not mean NO avalanche hazard. If heading out into the mountains today remember the snowpack has a poor structure on upper elevation slopes that have not avalanched and that were loaded by past winds (mainly North and East aspects). Hard wind slabs sit on faceted snow and/or buried surface hoar. Triggering a more dangerous slab that breaks in these layers is unlikely, however with the variability across the region, it’s not impossible. Thin rocky areas and steep convexities with poor snowpack structure are most suspect. As always practicing safe travel protocol is key (exposing one person at a time, grouping up in safe zones and having an escape route planned). Looking at potential consequences of even a small slide in complex steep terrain is an important consideration. 

Buried surface hoar found in a pit on Repeat Offender yesterday. 1.10.17. This layer was not reactive but still intact. 

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

Glide avalanches this week? Continued warm temperatures at the upper elevations over the past couple days may have enhanced ‘glide’ in the snowpack. Watch for glide cracks opening up and always avoid spending time underneath as they may release. Last week 3 glide cracks released. Known cracks exist on the South face of Eddie’s, Goldpan (behind the Magnum ridge), East face of Seattle Ridge (Northern end), Main Bowl and Southerly slopes near Johnson Pass. Anecdotally we have been observing cracks releasing as temperatures cool after a warm up. Today might be one of those days. 

 

 

Glide cracks in Main Bowl. 1.10.17

Weather
Wed, January 11th, 2017

Yesterday was clear, sunny and calm. The inversion was in place with ridge top temperatures above freezing and valley bottoms in the single digits. Overnight temperatures cooled slightly in the Alpine.

Today is forecasted to be similar with the exception of the inversion breaking down and cooling throughout the day into tomorrow as Arctic air moves in.  

Tomorrow will be colder and clouds are actually in the forecast tomorrow night in advance of a chance of snow Friday. Fingers crossed for actual accumulation. Timing and amounts of precipitation are still TBD.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 23   0    0  34
Summit Lake (1400′) 10 0  0  11
Alyeska Mid (1700′) 26 0  0  22

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  32  WSW 6   15  
Seattle Ridge (2400′)  32  variable 2    8
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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.