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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, March 17th 2016
Created: Mar 17th 5:55 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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.
0 NO RATING Below Treeline / Below 1,000'
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The Bottom Line

The avalanche danger is MODERATE in the mid elevation band between 1000’-3000’ where glide cracks continue to release naturally and without warning. In the Alpine, a generally LOW avalanche danger exists, but due to the glide problem below terrain choices remain limited. Chose your routes wisely to avoid glide cracks, and be on the lookout for changing conditions that could raise the danger in the alpine.  

*If you are headed to the Summit Lake area don't forget to check Summit Lake Summary, and click HERE for a recent observation of glide activity in that area.


Primary Concern

Glide cracks continue to avalanche daily and without warning throughout our region. Yesterday we spoke with two snowboarders who witnessed a glide release on the SW face of Tincan while they were on the Sunburst ridge. New glides avalanche debris was seen on the SE side of Seattle Ridge, S face of Max’s, and several new ones in the Twentymile drainage.

Glide cracks cover all aspects within the mid elevation band (between 1000-3000’) and remain a significant threat to popular terrain. As long as glide cracks continue to open up, move and release, we will stress the importance of avoiding them, which is THE ONLY WAY TO MANAGE THIS AVALANCHE PROBLEM. Remember these are totally unpredictable, release naturally and could be deadly if you were to get caught-up in that amount of snow. It is the entire winter snowpack releasing at the ground. 

A view of the SW aspect of Tincan where recent glide avalanches were observed yesterday from Sunburst. Click HERE to see more pictures of glide activity from the past week.

 

  Penguin Ridge experienced a very active cycle this week. Keep in mind the debris can run into snow free areas and threaten some summer trails, especially around Girdwood Valley and Portage.

 

 

 


Secondary Concern

Yesterday 3” of new snow was observed above 2000’ and only a trace is expected today. Easterly ridgetop winds ranged from 10-20mph and a similar pattern is expected today. Should winds trend towards the later or exceed 20mph, there is enough snow available for transport the hazard could rise. Pay attention for blowing snow along ridgetops and how well this new snow is bonding the surfaces below. Be aware of how the sun is heating up the new snow on solar aspects and if you see any obvious signs of instability like shooting cracks or recent avalanches be prepared to change your plans. Remember LOW danger doesn’t mean NO danger, one of these avalanche problems is still possible in very steep terrain.

Wind slabs: Yesterday there were several short periods of sustained 10-20mph winds and we did find one very small pocket that produced a shallow shooting crack along the Sunburst Ridge. Be on the lookout for pillows of newly drifted snow and active wind loading - it is possible that steep terrain could harbor tender isolated wind slabs.

Loose snow: Sluffs are fast moving and will be proportional to the slope you are on today.  Big terrain will yield big sluffs, particularly on cooler, drier northerly aspects.  On slopes with a southern tilt, wet loose avalanches could be initiated later in the day if we get windows of sunshine.  The biggest threat with both of these is the potential to get knocked off your feet in steep, committing terrain. 

Cornice fall: Very large cornice features loom over many ridgeline and have a tendency to break further back than expected. Give them lots of space, and limit exposure time under them. 

 

 


Mountain Weather

Yesterday skies were mostly sunny and mid elevation temperatures reached the low 40’s F.  Ridgetop winds were light from the SW with a short period of moderate winds that switched to an Easterly direction mid-day. Overnight temps were in the 20’s F and no new precipitation was recorded.

Today isolated snow showers are only expected to bring a trace of new snow. Skies will be cloudy, but patches of blue sky are possible. Easterly ridgetop winds could range from 10-20mph today and temperatures may increase into the mid 30’s F mid-day.

Tomorrow a similar pattern is anticipated with the next possibility for snow fall Friday night into Saturday.   

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31  134 
Summit Lake (1400') 30  43 
Alyeska Mid (1700') 31  trace  0.02  108 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24  SW - E  38 
Seattle Ridge(2400') 25  S - E  17 

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: Mar 25, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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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