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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Saturday, November 28th 2015
Created: Nov 28th 5:18 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
Alaska Airlines
Special Announcement

DANGEROUS AVALANCHE CONDITIONS REMAIN IN MANY AREAS around Southcentral Alaska.

Due to high avalanche danger the East Hatcher Pass Management Area is closed to public use until further notice. For current information visit DNR Newsroom  and hatcherpassavalanchecenter.org

The search for a missing skier in Hatcher pass continues today. Click HERE for latest media release from the Hatcher Pass Avalanche Center. 

An avalanche was reported yesterday near Anchorage in the Front Range on the Powerline Pass trail. Limited information is known at this time, but warrents extra caution on all hiking trails near steep terrain in Southcentral Alaska.  Click here for observation and photos.    


The Bottom Line

CONSIDERABLE avalanche danger exists both in the Alpine and at Treeline. Due to a four day rain event wet saturated snow up to 3’ thick could be triggered below 2500’. At higher elevations heavy snow is sitting on top of cold weak snow below making it possible to trigger a large slab avalanche up to 4' thick on all aspects. Avoid steep slopes and high consiquence terrain features. Careful snowpack evaluation, cautious route finding and conservative decision-making are essential skills if venturing into the mountains today. 

NO RATING below Treeline (below 1000’) means there is currently not enough snow to produce an avalanche at this elevation band.  


Primary Concern

Over the last three days 4" of water fell in the form of rain at lower elevations in Turnagain Pass. Rain/snow line fluctuated between 1800’ and 2500’ leaving the snow saturated with water. Several large wet avalanches were observed along the Seward Highway and Portage Valley over the last two days. Warm temperatures will persist today making it possible to trigger a wet avalanche on steep terrain features. Avoid this hazard by choosing low angle terrain away from large slopes and terrain traps. 

*If temperatures drop below freezing this concern will stabilize quickly as water drains and the slab strengthens in the mid elevation zone. 

Debris from a wet avalanche in Portage Valley. This avalanche likely released on the morning of Nov.27th.


Secondary Concern

Strong Northeast winds topped out at 109 mph on Sunburst weather station yesterday morning. Windslabs over 4’ thick on leeward aspects and crossloaded terrain features are a concern for today in the upper elevation zone. Avoid smooth pillow shaped snow on steep slopes and convexities. Even small features if steep enough could break well above you and have plenty of volume to bury a person. Obvious clues like shooting cracks and whumpfing sounds may not be present today making this avalanche problem difficult to identify. 


Additional Concern

In the upper Alpine above 2500’ weak faceted snow that formed during a cold snap has been covered up by 4’ of heavy snow creating an upside down snowpack. Last week observations showed a large variation in the distribution of this weaker snow below. It is likely that Northern aspects will harbor the bulk of this problem, but until more information is gathered much uncertainty exists as to how well this new snow has bonded with the older less stable snow below it. This is just one more high consequence reason to avoid steep terrain today. 


Mountain Weather

A very wet and warm storm passed through Southcentral Alaska leaving the region with above freezing temperatures and high-sustained winds for multiple days. In Turnagain Pass rain/snow line reached 2500’, Easterly ridgetop winds maxed out above 100mph and 4” of water fell over a three-day period. 

Showery weather in the form of mixed rain and snow is expected today and into the weekend with rain/snow line moving to 1000’. Temperatures will hover just above freezing (32F) and begin to cool slightly by this evening. Easterly ridgetop winds 20-30mph are also expected to depreciate by early evening. This pattern will continue through the weekend with patches of clear sky at times. 


*Seattle Wx Station wind data is currently not available.

PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32F  1.4  25 
Summit Lake (1400') 33F  0.2 10 
Alyeska Mid (1700') 34F  2.0   13.5

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 26F  NE  23  98 
Seattle Ridge(2400') 28F  *N/A  *N/A   *N/A  

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

Subscribe to the Turnagain Area Avalanche Advisory:

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
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