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Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, January 19th, 2013 - 7:00AM
Expires
Sun, January 20th, 2013 - 7:00AM
Forecaster
Kevin Wright
The Bottom Line

Some snow this afternoon with moderate wind combined with the lingering deep persistent slab will keep us at MODERATE above treeline.   Fresh wind slabs will start to form today and get bigger by tomorrow.   The deep slab problem is the most dangerous specific issue.   While triggering the deep slab is becoming less likely, the consequences remain high.   Below treeline the danger is LOW.

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Sat, January 19th, 2013
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
Low (1)
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

The primary concern today is still the deep slab, which is becoming more stable over time.  We haven’t had reports of deep slab avalanches since Monday when the last storm system ended.  The snowpack is showing evidence of strengthening, but a number of tests consistently still show a low probability of initiating a large avalanche. 

This kind of deep slab problem needs to earn our trust.  We have growing confidence, but only to a certain point.  The consequences of causing a full depth avalanche still deserve our respect and some alteration in our terrain choices.  Areas with thinner snow cover are more suspect, and steep rocky terrain may hold the trigger points that could activate a large avalanche.

Now that the deep weak layer has been dormant for a few days we can expect a low possibility of triggering it.  A new significant snow load (which is in the weather forecast for tonight) will increase the chances of deep slab activity as additional stress gets added to the weak foundation (see picture below). 

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

The small amount of snow predicted to fall this afternoon will build wind slabs at higher elevations.  Based on the timing of this storm it looks like this problem will be minor today, but may build into a significant problem tomorrow. 

Weather
Sat, January 19th, 2013

A blizzard watch is in effect for Girdwood, Seward, and Whittier starting this evening.   It appears that this will not have a major effect on the daylight hours today, but it may cause a bump in the avalanche danger by tomorrow.   We can expect increasing wind and up to 5 inches of snow by this evening.  

If you are wondering how the mountains are doing for snow this year check out the graph below.   Our snow depth is slightly above average, and the Snow Water Content measured at 1880 feet at Turnagain Pass (below) is just barely below average.  

SWE

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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
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Closed
Primrose Trail
Closed
Resurrection Pass Trail
Closed
Snug Harbor
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South Fork Snow River Corridor
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Summit Lake
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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.