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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, December 16th 2012
Created: Dec 16th 6:50 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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Alyeska Pipeline Service Company
The Bottom Line

ANNOUNCEMENTS
We would like to send a HUGE thank you to BRP and AMDS as a brand new 2013 Ski Doo REV-XM 800cc snowmachine was granted to the Friends of the CNFAIC through a generous loaner program. As a longtime supporter of the avalanche center, AMDS recommended this machine to benefit the entire backcountry community. Thanks also to the folks who joined us in the opening of the Turnagain Pass motorized area for the unveiling of the new sled and an avalanche condition synopsis!


BOTTOM LINE
We continue to have a MODERATE avalanche danger above treeline for lingering wind slab avalanches. These have been releasing on all aspects and yesterday three people were able to trigger three slides (see below). The MODERATE danger we are dealing with today is a:  low probability with high consequence situation - the larger the terrain, the larger the avalanche possible. This is a good thing to keep in mind with the variable snow conditions, size of the slabs and terrain you are riding in. Below treeline there is a LOW danger due to the lack of a slab.


Primary Concern

There were three wind slab avalanches triggered by skiers/snowboarders yesterday. Two on the Sunburst SW aspect on a wind loaded rollover and one on a westerly aspect of Tincan. All were between 2,700’ and 3,000’ in elevation and were small to medium in size - a few more details HERE. We have also had more reports and photos come in of older natural wind slabs that were likely triggered Thursday morning (Todd’s Run, N shoulder of Tincan Ridge and SW Sunburst).

During the past week we have had moderate to strong winds from all directions that have created an extremely variable snowpack. The riding conditions are not something to write home about and neither are the avalanche conditions. Areas that are scoured to the rocks sit right next to wind loaded slabs with the potential to release.

Good travel practices and thoughtful terrain management are key – a few important ones for today:

1-      Expose only one person at time
2-      Watch for recent avalanches
3-      Don’t discount collapsing and whumphing


Secondary Concern

The slabs mentioned above are taking a long time to heal because they are sitting on weak faceted snow formed during the November/early December cold spell. Faceted snow is very tricky and there is way too much of it in our pack. It can become dormant for a while once the pack adjusts to a new load, then with a little wind or snow, rear its head - this is pretty much what we have seen this season so far. Just remember when you are dealing with facets and persistent weak layers (including surface hoar) they are “guilty until proven innocent”.

Below treeline the snowpack has been sheltered from the wind and has broken down to becoming one unconsolidated unit. There are a multitude of weak layers but there is not a slab on top.


Mountain Weather

Temperatures have PLUMETED to a new seasonal low on the ridgetops. Sunburst and Seattle Ridge have dipped to -5F and -3F this morning where they are expected to increase only a few degrees today. There is not much of an inversion as sea level and parking lot temperatures hover between 5F and -10F. The light NW winds that were near 10mph overnight look to pick up to the 25mph range by this afternoon which should keep things feeling quite cold.

Our hopes for more snow this week is diminishing as the low pressure system moving into the Gulf on Tuesday looks to dig further south and just brush our neck of the woods. We could get a few flurries that spill over but stay tuned in case things change in our favor.

 


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). 

Graham will issue the next advisory Monday morning, December 17th.

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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