Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Sunday, January 12th 2014
Created: Jan 12th 6:27 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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.
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The Hoarding Marmot
The Bottom Line

The general avalanche hazard is MODERATE above and below treeline.  However, dense slabs up to 3’ in depth could be triggered in steep upper elevation terrain.  In these areas the avalanche hazard is CONSIDERABLE due to the potential for avalanches to be large. 

The likelihood of triggering avalanches will increase if people venture onto steep slopes, rollovers or convexities.  The likelihood will become greater in this type of terrain where the snowpack is shallow.  It is in these spots where humans are more likely to affect weak layers and produce avalanches.  The consequences, or result of an avalanche have the potential to be severe.  Consequences will be greater in the higher elevations where the overall slab depth is greater.

Primary Concern

It has been a week since significant precipitation or loading has occurred in the area.  All of our information over the past seven days has come from tests in snow pits in the mid and lower elevations.  The general trend in our tests has shown us that it is slowly becoming more difficult to trigger an avalanche.  The one variable that has remained the same is the potential for avalanches to propagate across entire slopes.  This fact alone has kept us tip toeing around the mountains lately.  Travel into the more suspect areas (e.g. upper elevation starting zones and steep terrain) has not happened.  This makes it more difficult to truly have a comprehensive understanding of the snowpack.

The foundation of the snowpack is weak.  Faceted snow near the ground is prevalent throughout the area.  The slab that has formed over the past month is between 1 and 3 feet deep, depending on elevation (deeper in the higher elevations).  This slab is strong enough in many areas to support the weight of a person or snowmachine.  The areas where that is not the case are:

Steep rollovers & convexities.
Steep open slopes, generally above 35 degrees and certainly above 40 degrees.
Thin spots in the slab.  Areas with shallow snow that are connected to areas with deeper snow, commonly found along ridgecrests.

It is worth avoiding these areas for the time being.  The weak snow near the ground simply needs more time to adjust to the slab above it.

Mountain Weather

In the past 24 hours the mountains around Eastern Turnagain Arm have received no new snow.  Temperatures have averaged 12 degrees F at ridge tops.  Wind direction has shifted overnight and is currently blowing out of the East.  The 24 hour average wind speed was 5mph with gusts to 23mph.

Today will bring another uneventful day in terms of weather in the mountains.  Temps at 1,000’ will reach the mid 20s F.  Winds will remain light out of the East.  There is a slight chance for snow during the day with little accumulation expected.

The beginning of this coming week looks to bring continued clouds and light precip to the area.  The long term outlook is starting to show the potential for more significant precipitation by the middle of the week.

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).

Winter snowmachine use open/closed status and riding conditions updates

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: Nov 18, 2017 )

Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.

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