Avalanche Advisory

Turnagain Area Avalanche Advisory Saturday, February 22nd 2014 6:54 am by Kevin Wright ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.

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We have a couple reports of human triggered avalanches from the last 2 days.  The faceted weak layer is suspected for these avalanches (read on in the primary concern). 

We got a report from an avalanche that occurred on Thursday in Seattle creek in Warmup bowl - the report is of a deep avalanche triggered by a snowmachiner that caught and carried the rider a significant distance to the bottom of the bowl.  Crown face was up to 5 feet deep, involving part of the cornice, and was 300 feet wide.  There was an effective airbag deployment, and nobody was reported buried or injured.  

The second report is from yesterday at the Cornbiscuit/Magnum Headwall.  One skier was carried about 50 feet in a slide with a crown face up to 2 feet deep.  See this observation for a first-hand description.

With these kinds of reports we know that steep terrain that harbors the facets can produce avalanches.  The danger rating is at MODERATE for this specific problem.  

Show the Complete North American Avalanche Danger Scale

North American Public Avalanche Danger Scale Avalanche danger is determined by the likelihood, size and distribution of avalanches. Danger Level Travel Advice Likelihood of Avalanches Avalanche Size and Distribution 5 Extreme Avoid all avalanche terrain. Natural and human- triggered avalanches certain. Large to very large avalanches in many areas. 4 High Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Natural avalanches likely; human- triggered avalanches very likely. Large avalanches in many areas; or very large avalanches in specific areas. 3 Considerable Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential. Natural avalanches possible; human- triggered avalanches likely. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. 2 Moderate Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Natural avalanches unlikely; human- triggered avalanches possible. Small avalanches in specific areas; or large avalanches in isolated areas. 1 Low Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Natural and human- triggered avalanches unlikely. Small avalanches in isolated areas or extreme terrain. Safe backcountry travel requires training and experience. You control your own risk by choosing where, when and how you travel.

2 Moderate Alpine / Above 2,500'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2 Moderate Treeline / 1,000'-2,500'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

2 Moderate Below Treeline / Below 1,000'

Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Thanks for all the field observations from the public.  This is a huge asset to inform others of avalanche events and increases our collective knowledge of the snowpack.  Remember, you can use the online form or give us a voicemail using the hotline (754-2369 press star to go straight to voicemail).

Avalanche Problem 1

The most common snowpack problem continues to be a weak layer of facets on top of the hard melt/freeze crust from January.  We can't find the facets everywhere, but they are common at and above treeline.  All the February snow (51 inches of storm accumulation at Turnagain Pass) now sits on this weak layer.  Snow pit tests are showing moderate to hard force required to collapse the facet layer.  In many places that failure will propagate across an extended column (this video shows an example from last weekend).

Last weekend we had many avalanches reported on this weak layer.  Check the observations page for photos and descriptions of those slides.

People are starting to explore farther back into the mountains.  Steeper slopes are getting tested, which has resulted in the two known human triggered avalanches in the last 2 days.  Avoiding or minimizing exposure to steep terrain is the safest bet with the current problem.  We still have plenty of untracked snow on slopes less than 35 degrees.  If you do find yourself in the steeps, careful terrain management by exposing only one person at a time and avoiding terrain traps will be essential.  

It hasn't snowed in several days now, since the 18th.  Wind has also stayed minimal since that last snowfall.

Today's expected weather is mostly cloudy with a chance of snow (less than 1 inch).  Wind may pick up, 20-35mph from the Southeast and increase more tonight.

Sunny weather is forecasted for Sunday and Monday.  Overall we are staying in a calm weather pattern.  Check the weather page for more detailed information.  

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).

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Dec 01, 2018 )

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