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Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Thu, January 10th, 2013 - 7:00AM
Expires
Fri, January 11th, 2013 - 7:00AM
Forecaster
John Fitzgerald
The Bottom Line

The hazard remains at CONSIDERABLE above treeline today, where large destructive avalanches are possible.   The likelihood of triggering large avalanches is on the decline, but the consequences of being caught are dire.   The hazard below treeline is MODERATE today where human triggered avalanches are still possible.   Conservative terrain choices are critical today.

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Thu, January 10th, 2013
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
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 biggest concern.  The number of avalanches that are occurring is low, but the potential size and destructive force is very high.  We received another wake up call on Tuesday, as a snowmachiner remotely triggered a very large avalanche on Seattle Ridge where amazingly no one was buried or injured.  This avalanche had the potential to do a lot of damage.  This is the second such event in the last week

Clear skies yesterday gave us a chance to look around the Turnagain Pass area.  We were able to see a lot of old crowns that have filled in as well as one recent natural avalanche above Seattle Creek that caught our attention.  With forecasted weather not likely to change the overall hazard in the coming days, the potential for large destructive avalanches will remain.

Typically a person or snowmachine can affect a weak layer within a few feet of the surface.  The new slab formed over the Christmas through New Years period is 6-10 feet in many areas.  The most likely places to find a thin spot in the slab is above treeline where winds have created greater variation in slab depths.  
Weak layers formed between October and December are widespread.  It is safe to assume that almost anywhere you go in the mountains there is a weak layer somewhere below you.  This thick slab/weak layer combo is what is allowing for these large avalanches to occur. 

Traveling on lower angled slopes and avoiding large open terrain is your best bet for avoiding this unmanageable problem today.

Avalanche Problem 2
  • 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

Light to moderate winds have created small pockets of shallow new wind slab.  Light density snow resting on the surface will get blown around easily today.  The consequences of this problem increase in steep terrain and above terrain traps.

Weather
Thu, January 10th, 2013

In the past 24 hours temps have remained in the 20s F, winds have been light to moderate averaging in the teens/twenties out of the E and SE with gusts to 38mph.   Light snow has begun to fall on Turnagain Pass and in the Girdwood Valley this morning.

In the mountains today we should expect to see light snowfall mainly in the morning with a few inches of accumulation possible.   Ridgetop winds will be out of the SE averaging 15-20mph and temps at 1000′ will be in the mid 20s F.

The extended outlook calls for light precip each of the next 3 days with temps warming as a series of weak low pressure systems move through the area.

_______________________________________________________________________________________________________

Wendy will issue the next advisory tomorrow morning, January 11th.

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Riding Areas
Updated Mon, October 26th, 2020

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Placer River
Closed
Skookum Drainage
Closed
Turnagain Pass
Closed
Twentymile
Closed
Seward District
Carter Lake
Closed
Lost Lake Trail
Closed
Primrose Trail
Closed
Resurrection Pass Trail
Closed
Snug Harbor
Closed
South Fork Snow River Corridor
Closed
Summit Lake
Closed

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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.