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ARCHIVED - Forecasts expire after 24 hours.
Mon, January 14th, 2013 - 7:00AM
Tue, January 15th, 2013 - 7:00AM
John Fitzgerald
Avalanche risk The Bottom Line

The hazard is CONSIDERABLE above treeline today, where human triggered avalanches are most likely in steep wind loaded starting zones.   Below treeline the hazard is MODERATE, where it is still possible for skiers, riders and snowmachiners to trigger avalanches.

Mon, January 14th, 2013
Above 2,500'
3 - Considerable
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
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
  • Deep Persistent Slabs
    Deep Persistent Slabs
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
More info at Avalanche.org

Deep slab avalanches continue to be our greatest concern.  This most recent load of snow, while dense, is probably not enough to drastically increase the likelihood of triggering these large and destructive avalanches.  The weak layers formed in October and November are now buried 4-10 feet in many areas, and are getting more difficult to impact with the weight of a person or snowmachine. 

Areas to avoid today are trigger points in upper elevation starting zones, where those weak layers are only covered by 1-3 feet of slab.  If you’re able to hit one of these spots, the potential for avalanches to propagate across large areas remains very high.  What this means is that the chances of starting one of these avalanches is low to moderate but the consequences are very high.  Human triggered deep slab avalanches in the past two weeks have produced impressive amounts of debris, and still warrant our attention. 

Avalanche Problem 2
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

With a gradual rise in temps over the past 2 days, we have an “upside down” scenario in the upper layers of the snowpack.  Pit tests at treeline yesterday on Tincan revealed this weakness and showed potential for propagation across slopes.  AKDOT was also able to trigger many avalanches around Bird Flats and Girdwood in the storm snow yesterday.  While the storm snow totals were higher in these areas, the general trend of warming over the past 48 hours is similar in both places.  Expect this problem to resolve itself more quickly than the deep slab problem.

Mon, January 14th, 2013

In the past 24 hours Turnagain pass has received ~8″ of new snow with .8″ water.   Winds have been light to moderate out of the East averaging in the teens with gusts to 49 mph.   Temps at 1800′ have been around 32 with temps at ridgetops in the mid twenties.
The biggest news in weather is that the forecasted rise in temperature and heavy precip did not come to fruition on Turnagain Pass.   The Girdwood Valley has seen almost twice the amount of precip in the past 24 hrs.
Look for precip to taper off today and temps to start gradually dropping with freezing levels descending to sea level by tonight.
The extended outlook calls for a break in precip later today into Tuesday with snowfall returning by midweek.   Temps will be significantly cooler through the next 3 days.


Wendy will issue the next advisory tomorrow morning, January 15th.

Recent Observations for Turnagain Pass
Date Region Location
02/25/24 Turnagain Observation: Kickstep NE Bowl
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02/21/24 Turnagain Observation: Tincan Trees
02/21/24 Turnagain Observation: Sunburst
02/20/24 Turnagain Avalanche: Tincan
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02/19/24 Turnagain Avalanche: Base of Seattle Ridge
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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.