Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, April 9th 2016 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is CONSIDERABLE in Turnagain Pass due to rain, blowing snow and glide avalanches. Below 2500’ large destructive glide avalanches and human triggered wet loose avalanches are possible today. In the Alpine fresh wind slabs, 1’-2’ thick are possible where the snow is drier and winds are strong. Cautious route-finding and snowpack evaluation will be essential, and it will be extra important to avoid being under the runout of glide cracks.

Today's avalanche problems are in order of encountering them while ascending in elevation and today's storm should warrant extra caution as the danger increase throughout the day.  If more precipitation falls than expected and winds remain strong, today’s avalanche danger could increase to HIGH.  Be on the lookout for Natural avalanche activity and adapt to changing conditions.

Summer use trails with avalanche terrain above should be avoided due to natural avalanche activity from above. Byron trail in Portage Valley is not a recommended and the Turnagain Arm Trail between Bird and Girdwood, remains CLOSED.

*If you are headed to the Summit Lake area don't forget to check Summit Lake Summary

 Show the Complete North American Avalanche Danger Scale
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'
Special Announcement

The Chugach National Forest will be closing some riding areas to motorized use today 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) will remain open. 

Avalanche Problem 1

The possibility of wet loose avalanche activity will increase throughout the day with rain saturating the snowpack in the Treeline zone. Rain (~0.76") is expected up to 2000’ and could weaken the superficial surface crust. 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. In the mid elevation where wet snow is falling on a slick bed surface, triggering a wet loose avalanche could be especially dangerous at the bottom of a terrain trap or on a large slope. Monitor the depth of this wet heavy snow, and stay off of slopes steeper than 35 degrees if the snow is wet and saturated.

Avalanche Problem 2

Glide cracks continue to be actively releasing in popular terrain. On April 7th between 4:51pm and 5:07pm, Turnagain DOT web camera (currently not available online) photographed a very large glide above part of the uptrack. The debris covered many recent snow machine tracks traversing to & from the uptrack as well as recent high marks in this area. The good news is nothing bad happened, and no one was caught during a sunny afternoon at a popular time of day. The bad news is there are more cracks in this area that still threaten the uptrack.

Today increasing avalanche danger and poor visibility will make the decision ‘not to go’ into this area easier. Also be aware that rain and wet snow will be adding stress to glides today and we may see a spike in glide releases again over the next few days. Remember avoidance is key; if you were to be in the wrong place at the wrong time getting caught up in a glide avalanche would be unsurvivable. 

Repeat Offender near the Seattle Ridge Uptrack. Photo taken at 10:30am on 4/9. 

Additional Concern

Yesterday blowing snow was observed in the alpine as Easterly winds started building from the East. These winds increased overnight averaging in the 30-40’s mph with gusts in the 60’s mph. Around three inches of new snow fell overnight and another 5-10” is expected above 2000’. Fresh and tender winds slabs will be forming on a slick bed surface and could be a thick as 1’-2’ deep on leeward terrain features and along ridges and gullies. Small test slopes and hand pits will be good ways to test the snow as you gain elevation. Monitor snow depths and look for any signs of unstable snow like shooting cracks or recent avalanches. Today it will be important to stick to mellow terrain by keeping slope angles below 35 degrees.

Cornices: Blowing snow will be adding stress to cornices today and natural activity is possible. Some cornices are gigantic this winter and skier or snowmachiner could be the tipping point should someone get too close.  Remember they have a tendency to break much further back than one might expect. Give them extra space and avoid travel directly below cornices. 

Yesterday an observer in the Taylor Pass/Pastoral area experienced building winds and blowing snow starting around 2pm yesterday.  Photo by Liz Repetto.

Mountain Weather

Yesterday skies were clear in the morning becoming cloudy in the afternoon. Ridgetop winds started building mid day becoming strong by early evening, averaging in the 30-40’s mph overnight. Yesterday temperatures reached the mid 40F’s at 1000’. Overnight temperatures at Center Ridge Weather Station remained above freezing with a low of 32F at 1am. 1” of new snow was recorded and .2” of water.

An approaching front is bringing widespread showers and strong winds to Southcentral Alakska. Today 0.76” of water is expected in the form of rain below 2000’, and 5-10” of new snow could fall in the upper elevations. Strong Easterly winds will persist into the early afternoon becoming Moderate by early evening. Daytime temperatures at 1000’ are expected to reach the low 40F’s and remain above freezing overnight.  

Overnight and into tomorrow an additional 0.9” of water is expected and winds will remain Moderate from the East. Temperatures may start to cool slightly, with rain/snow line ~1500’. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 37  0.2  115 
Summit Lake (1400') 39  34 
Alyeska Mid (1700') 36  .39  102 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  NE  20 75 
Seattle Ridge(2400') 30   SE 21   58

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: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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.

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