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Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, January 18th, 2013 - 7:00AM
Expires
Sat, January 19th, 2013 - 7:00AM
Forecaster
John Fitzgerald
The Bottom Line

The hazard above treeline today is MODERATE, where it is still possible for a person or snowmachine to trigger a large destructive avalanche.   Below treeline the hazard is LOW today, where it is unlikely for humans to trigger avalanches.   Remember that ‘LOW’ does not mean ‘NO’. The main concern below treeline is being under large, open terrain that has the potential to produce high volume avalanches that can run into the lower elevations.

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Fri, January 18th, 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

Deep slab avalanches are the primary concern for today.  Large, dense and potentially deadly slabs continue to sit on a weak foundation.  Clear and cold weather for much of October, November and the first half of December created thick layers of weak, faceted snow.  The steady stream of moisture beginning around Christmas formed the deep slab that we are worried most about.

At this point, it is getting more and more difficult to trigger these avalanches.  But make no mistake; getting tangled up in one of these avalanches has the potential to do a lot of damage.  It is common for this type of avalanche problem to lay dormant for extended periods of time.  It has been 4 days since any natural avalanche activity and 3 days since any human or explosively triggered avalanches have been reported.  With clearing skies and good visibility it will be tempting to venture onto steep terrain.  Do not forget what is down below your feet or sled-weak rotten snow capable of producing very large avalanches.  It is unlikely that the normal warning signs of recent avalanches, shooting cracks or collapsing will be present prior to a deep slab avalanche releasing.

Pit tests over the last several days continue to illustrate this problem well.  The weak layer is hard to impact, but the outcome once it is affected translates to large avalanches propagating across wide areas.

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

Very small shallow (<6″) wind slabs formed yesterday in the higher elevations, where light density snow was easily transported by light to moderate winds.  We witnessed very small shooting cracks in the surface snow above treeline yesterday.  While this problem is relatively minor, it is worth paying attention to today in upper elevation starting zones.

Weather
Fri, January 18th, 2013

Precip, winds and temps have not done anything dramatically in the past 24 hours to change our avalanche problems for today.
Light veering winds overnight have given way to current temps in the single digits at ridgetops and mostly clear skies.   No new snow has been recorded in the past 24 hours around Turnagain Arm.
The weather for today looks to be partly cloudy and cooler, with winds out of the NW at 5-15 mph, temps in the teens and no precip expected.
The extended outlook is calling for the next chance of snow on Saturday, as a low pressure system to our SW moves towards the region.

___________________________________________________

Kevin will issue the next advisory tomorrow morning, January 19th.

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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.