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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Saturday, January 14th 2017
Created: Jan 14th 4:18 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
 Show the Complete North American Avalanche Danger Scale
The Hoarding Marmot
Special Announcement

Join us TODAY, Saturday, at Hatcher Pass from 11am-1pm for a FREE rescue workshop!! This event to brought to you by Hatcher Pass Avalanche Center, the CNFAIC, the Alaska Avalanche School, AAIC and hosted by the Hatcher Pass Snowriders Club. More info HERE

* Hatcher Pass continues to have unstable conditions and received new snow, check the Hatcher Pass advisory HERE if you are thinking of heading there this weekend.


The Bottom Line

The avalanche danger is CONSIDERABLE on upper elevation slopes. Human triggered wind slabs 1-2' thick are likely on leeward terrain and natural avalanches are possible. In areas unaffected by winds and receiving less snow the danger will be MODERATE where small shallow storm slabs and sluffs in the new snow may be triggered on the steeper slopes.  Girdwood Valley received twice as much snow as Turnagain Pass.

Ice climbers and hikers:  In Portage Valley and other areas where climbing routes and trails sit under avalanche paths, be aware that debris from a naturally occurring slide above may run to these lower elevations.

Check out the Saturday Summit Lake Summary HERE. 

 


Primary Concern

New snow (6+ inches at Turnagain and 12+ inches in Girdwood Valley) combined with moderate winds speeds ESE-ENE 15-25 (gusting to 40 mph) in the last 24 hrs have formed fresh, sensitive wind slabs on leeward slopes. Wind slabs may be 1-2' thick. These slabs will be sitting on a variety of old surfaces and may not bond well. Slick wind crusts and soft facets covered most of the terrain prior to the storm. Places where the new snow landed on the slick crusts will be especially suspect. Look for new cornice formation, pillowed and drifted snow and cracking. Winds speeds have mellowed this morning but are expected to pick back up this afternoon. Watch for wind transporting snow and avoid travel underneath actively loading slopes as naturals will be possible. 

 Photos: National Avalanche Center 

 

 

Yesterday afternoon. 1.13.17, Snow starting to drift and crack. 

 


Secondary Concern

In areas unaffected by wind new snow can still act as a slab especially in Girdwood where more snow fell. In addition temperatures warmed up overnight and the storm snow may be slightly upside down with heavier snow over lighter snow. The question during and right after a storm is "How well is the snow bonding to the old snow surface it landed on?" As noted above with the wind slabs, the storm snow landed on a variety of surfaces including slick wind crusts and may not initally bond well. Stepping off the skin track or jumping off your snowmachine to do quick hand pits will be a great tool for determining new snow depth and bonding. Also be on the lookout for loose snow avalanches in the steep terrain where the storm snow may not stick to old surfaces at all. Avoid terrain traps i.e. places where shallow avalanches could pile up more deeply and look for cracking.

As always practicing safe travel protocol is key:

1) Expose only one person at a time

2) Group up in safe zones 

3) Have an escape route planned 

4) Pay attention to other groups. This could be a busy holiday weekend! 


Additional Concern

Glide cracks have been slowing opening this week; though we have not seen/heard of any new cracks releasing. Keep an eye out for cracks, which is difficult with new snow and wind, and limit time underneath them. Main Bowl is one of the spots where glide cracks threaten terrain that is commonly traveled.


Mountain Weather

Yesterday snow fell throughout the day with intensity picking up late in the afternoon. Winds were easterly 15-20 mph with gusts into the 30s and 40s. Temperatures were mostly in the 20Fs with a band of warm air at road level in Turnagain Pass in the 30Fs. Overall temperatures warmed slightly overnight and winds speeds dropped. 

This morning the skies are clearing on Turnagain but snow showers continue in Girdwood. These are forecasted to taper off to partly cloudy skies. Colder air will move in this afternoon with westerly winds to 15-25 mph. Temperatures will drop into the single digits tonight. The next storm system is forecasted to arrive tomorrow with another round of snow into Monday. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33   7  .6 40 
Summit Lake (1400')  21  3 .4   14
Alyeska Mid (1700')  28  13  1.4  35

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  22 ENE  18  40 
Seattle Ridge(2400')  24  SE  15  29

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 15, 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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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