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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Saturday, March 12th 2016
Created: Mar 12th 6:18 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
Tesoro Foundation
Special Announcement

Tune-up your avalanche skills for Spring Break, play in the flats and let the snowpack adjust today! 

  • TODAY - Saturday, March 12th join us at Turnagain Pass for a FREE Avalanche Rescue Workshop from 11 am-12:30 pm at the motorized lot. This class is open to everyone. Please bring your beacon, shovel and probe. For more info click HERE. Look for the blue CNFAIC Avalanche trailer.

Photo of the set up yesterday at the motorized lot for today's event:
     


The Bottom Line

There is a CONSIDERABLE avalanche hazard today above 1,000' where upwards of a foot of new snow has fallen with strong winds. A variety of avalanche problems are out there and the one most likely to impact a person are fresh wind slabs 1-2' thick. These slabs are likely to be triggered by a person and could release naturally with warming by the sun. Additionally, wet loose snow avalanches will be likely on steep sunlit slopes. Cornice falls are possible as well today and glide avalanches continue to release. 

**Today's message is to go into the backcountry with a conservative mind set. Constantly assess the new snow. How it is sticking (or not sticking) to the old surfaces? Keep in mind that it is springtime and sunshine will be a trigger for avalanches. Safer areas to recreate will be in mellow terrain with slopes less than 35 degrees.

If you are headed to Summit Lake, check out today's weekly summary HERE.


Primary Concern

A quick hitting storm rolled through the region yesterday bringing a much needed 're-fresh' to Turnagain Pass. The Turnagain Pass SNOTEL station reported 9" of new snow beginning yesterday around noon and ending last night around midnight. This usually equates to around a foot in the Alpine. The rain/snow line was hovering just under the parking lot elevations on the Pass, around 1,000'. We did get a report of a natural avalanche seen across the Arm from Girdwood, see that and additonal info HERE. This new snow is great news, but a new set of avalanche conditions will come with it as well. These are:

Wind Slabs:  Winds associated with the snowfall were moderate to strong from a generally Easterly direction. This is a perfect recipe for forming wind slabs above treeline that could be anywhere from 1-2+' thick. How well these fresh slabs are bonding with the old snow surface is uncertain - and something to be wary of today. The old snow surface was quite variable, harboring sun crusts on Southerly aspects, wind crusts and loose faceting snow. All of these surfaces are not likely to promote good bonding right away and our hackles should be up. Things to watch for today:

   1-  Recent avalanches, the skies should clear for good visibility
   2-  Cracking or collapsing in the new snow
   3-  Slopes that have been windloaded - Avoid these today, give them a chance to adjust
   4-  SUN.... If the sun comes out slabs could release naturally with the warming!

Loose Snow Avalanches:  Once the sun does come out (today or tomorrow) damp/wet sluffs are likely to run naturally. These will also be easily triggered by a person. Sluffs should entrain mostly just the new snow, so how much new snow is on a slope will depend on how large the sluff is. 

Cornices:  Another round of snow and wind will only add to the weight of these truck size features overhanging many slopes. Extra caution is warranted when choosing how you travel along ridgelines - give cornices an extra wide berth. Also, limit time under these, they could fall on their own and the sun warming them will add to this possibility.


Secondary Concern

AVOID travel under glide cracks. This week has been a particularly active glide avalanche cycle. Glide cracks continue to threaten large areas of terrain throughout Turnagain Pass, Girdwood, and Summit Lake. There were several new glide avalanches seen Wednesday from the Seward Hwy, and a large glide released on the East face of Seattle Ridge a few days ago. Glide cracks are on all aspects within the mid-elevation band (1000'-2500'), and some areas like the SW face of Cornbiscuit and Tincan are covered. This avalanche problem is impossible to predict and is not associated with human triggers. We have been talking about the glide avalanche problem for over two months in the advisory and as long as glide cracks continue to open up, move and release, we will stress the importance of avoiding them


Mountain Weather

Yesterday saw a quick moving disturbance move through. Visibility was poor as rain fell below 800-1,000' with snow above. The Turnagain Pass SNOTEL site has reported 9" of new snow at 2,000'. Winds associated with the snowfall were 20-25mph from the East along the ridgetops with stronger gusts. Temperatures have been warm, in the mid 30's F at 1,000' and the mid 20'sF at 3,500'.

Overnight, snowfall has stopped and winds have died down. For today, skies should begin to clear up as the system exists the region; we are expecting the sun to come out for the afternoon. Winds today are expected to be light, 5-10mph, from a generally East direction and temperatures warm, up to 40F at 1,000' and the upper 20'sF in the Alpine. 

Sunday and into Monday looks to be mostly clear as well with sunny skies and light Easterly ridgetop winds.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31  0.9  143 
Summit Lake (1400') 35  43 
Alyeska Mid (1700') 32  0.7  110 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24  NE  18  43 
Seattle Ridge(2400') 26  SE  16  35 

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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