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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, April 14th 2016
Created: Apr 14th 6:02 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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'
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Alaska Rock Gym
Special Announcement
  • This is the final week of daily avalanche advisories. Between Monday, April 18th and Saturday, April 30th we will be issuing advisories on weekends and intermittently during the week
  • The Chugach National Forest has closed some riding areas to motorized use due to snow melting out. Please see the table at the bottom of this page for a complete list. Snug Harbor, Summit Lake and Turnagain Pass (N. of Granite creek) remain open. 

The Bottom Line

The avalanche danger is CONSIDERABLE below 2500’ due to a continued pattern of warm temperatures and an active glide avalanche cycle. Glide cracks have been releasing daily and without warning, and travel is not recommended in terrain with existing glide cracks (including the uptrack on the motorized side of Turnagain Pass.) Human triggered wet-loose avalanches will be possible on slopes steeper than 35 degrees and will be more likely later in the day with warming temperatures.

In the Alpine, above 2500’, a generally LOW avalanche danger exists. LOW danger does not mean NO danger – Be aware of your exposure in steep terrain and give large cornice extra space – these features should never be trusted.

*ATTENTION HIKERS: Summer use trails with avalanche terrain above should be avoided due to avalanche activity from above. Byron trail in Portage Valley and Crow Pass are two examples of trails not recommended right now. 


Primary Concern

Glide cracks continue to be actively releasing in popular terrain throughout our region including recent activity on Repeat Offender (photo below). Travel underneath existing glide cracks is a total gamble. The zone above and around the popular motorized up-track on Seattle Ridge continues to have our hackles up. This well traveled slope is hanging in the balance (pictured below). Although much of the snowpack has already avalanched along Seattle Ridge, there is still a lot of snow that could release. There was no overnight freeze in the 1000-2000' elevation band and there is the possibility of rain today. These weather factors may increase glide activity.

Due to the dangerous and destructive power of even a small glide avalanche, we are recommending that people do not travel in avalanche terrain (including runout zones) on the motorized side of Turnagain Pass (West Side). Glide avalanche hazard also exists on the non-motorized side of Turnagain Pass. Travel underneath existing glide cracks is not recommended; if you were to be in the wrong place at the wrong time getting caught up in a glide avalanche would not be survivable. 

Flat light and distance make it hard to see small cracks that have formed in the rocks directly above the up-track, looker right side of the photo.

 

 

A small glide release was observed on Repeat Offender last night with the DOT web camera just after 7pm. Before and after pictures below. 

 


Secondary Concern

Below 2000’ we have seen multiple days without freezing temperatures and yesterday’s sun left the snowpack wet and saturated in the mid elevation zone. This combined with the possibility of rain will up the likelihood and potential for human triggered wet loose avalanches today. If the snow becomes unsupportable and your skis/snowmachine start sinking into punchy wet snow, this is an obvious sign the snow is loosing its strength. Remember wet loose avalanches can be hard to escape once initiated and particularly hazardous if they push you into a terrain trap. 

 

Skier triggered rollerballs were easy to initiate by 3pm in the mid elevation zone yesterday. This was on a small slope of about 35 degrees.


Additional Concern

Today it will be important to be aware of terrain features that could harbor isolated instabilities in the Apline, above 2500'. Cornices remain large and warm daytime temperatures will be adding additional stress. Give them extra space and remember they have a tendency to break much further back than expected. On shaded aspects triggering an old wind slab will be especially dangerous in high consequence terrain. Ease into steep terrain with caution and be aware features (rocks and cliffs) where taking a fall would be undesired.  


Mountain Weather

Yesterday skies were partly to mostly cloudy with periods of sunshine throughout the day. At Center Ridge Weather station (1880’) daytime temperatures remained warm with a high of 47F mid-day and overnight temperatures hovering just above freezing level (33F.) Ridgetop winds were light from the East and a trace of precipitation (0.1”) was recorded overnight.

Light scattered showers are expected throughout the day with mostly cloudy skis. This will be in the form of rain below 2500’, around 0.1” of (snow water equivalent.) Light Ridgetop winds, 5-15mph, will be from the East.  Daytime highs for 1000’ will be in the mid 40F’s again and overnight lows in the mid 30F’s.

A similar pattern is expected again on Friday, but with a higher chance of rain/snow showers.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 39  rain 0.1  113 
Summit Lake (1400') 40  30 
Alyeska Mid (1700') 38  rain  0.01  98 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 31  ENE  17 
Seattle Ridge(2400') 32  SE  13  19 

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
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