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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, January 7th 2014
Created: Jan 7th 6:50 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.
 Show the Complete North American Avalanche Danger Scale
Special Announcement

For anyone who has taken an Avalanche Level 2 course and interested in a refresher check out the Alaska Avalanche School’s “Level 2 refresher/Observer Workshop”. The course will be a lot of fun and taught by CNFAIC’s Wendy Wagner and AAS’s Eeva Latosuo.


The Bottom Line

A CONSIDERABLE avalanche danger exists above treeline for triggering a large slab avalanche 2-3’ deep. Areas of most concern are steep slopes over 35 degrees on all aspects, especially those with prior wind loading. Below treeline the danger is MODERATE for triggering a slab avalanche ~2’ deep. These avalanches are breaking in weak snow near the base of the snowpack.

Conservative terrain selection is the key for a safe day in the backcountry. Safe places to recreate are slopes 30 degrees or less without steeper terrain above or connected to you.


Primary Concern

There was no new avalanche activity reported yesterday. Though once again, few people are venturing into avalanche terrain, including myself. We did get some additional photos sent in of the natural cycle that occurred two days ago (see photo below as well as the link). These avalanches were breaking in the weak snow near the ground and taking the majority of the snowpack with them. Triggering a large slab that sits on the brink is the essence of our primary concern.

Without much change in the weather, it will take a person, group of people or a snowmachine to trigger one of these avalanches. After this last storm the slab is becoming thicker, up to 3’ in places. This can make it harder for your weight to impact the weak layer at the base of the pack and trigger a slide - but the consequences are high.

Below is South facing Lipps Ridge on Turnagain Pass. Avalanche occurred naturally late on 1/4 or early 1/5 (SSW, 3,400’)
 

 

A few words on snowpack assessment:
Information has been limited since the end of the weekend’s storm. With little visibility and very few people testing the steeper slopes our main clues for evaluating the snowpack continue to be snow pit data and collapsing.

Snow pit data: What we are finding is a slab between 2 and 3 feet thick composed of all the December and January snow (4.8” water equivalent at 1880ft). Under this is the well documented weak faceted snow above and below the December drizzle crust. Stability tests are showing that it’s getting harder to collapse the weak layer(s), but once failure occurs all bets are off and large dangerous avalanches are likely if the slope is steep enough. 

Collapsing: Several people, including our staff, continue to report collapsing while traveling. This means a person can trigger a failure in the weak faceted snow and subsequently an avalanche. What this tells me is that even though the pit data says it should be hard to trigger a slide, maybe it’s not that hard after all. These obvious signs of instability should always trump pit results.

Below 1,500’ a series of crusts and wet snow make up the snowpack and triggering an avalanche is unlikely.


Mountain Weather

Yesterday morning a small system moving through added 1-2” of snow to the upper elevations on the Pass and .1” of rain below 1,500’. Alyeska, on the other hand, was favored and reported 6” on the upper mountain with rain at the base. Winds during the past 24-hours have decreased from the 20mph range to the 5-10mph range from the East and temperatures have remained in the 20’s on the ridgelines and low 30’s at 1,000’.

Today we should see mostly cloudy skies and warm Southeasterly flow with no precipitation. Temperatures look to remain in the mid 20’s above treeline and low 30’s below treeline. Ridgetop winds will be light from the Southeast in the 10mph range.

Tonight into tomorrow the warm conditions remain with a chance for 1-2” of snow and rain below 500’. The next good shot of precip is difficult to tell as the weather models are having a hard time with the extended outlook.

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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be 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.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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