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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Wednesday, February 4th 2015
Created: Feb 4th 5:52 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
The Woodland Family
Special Announcement

Attention Ladies: SheJumps, CNFAIC, and Alyeska Resort are joining forces to host a 2 hour avalanche companion rescue clinic at Alyeska Resort on Sunday, Feb.8 from 1pm-3pm. This is a free clinic for ladies only, and is a great place to practice your beacon skills. Click HERE for more info.


The Bottom Line

A LOW avalanche danger exists over most of Turnagain Pass, with pockets of MODERATE danger on wind exposed areas of the forecast zone. Old wind slabs 8-10” can be triggered if found on slopes steeper than 40°.  


Primary Concern

Today looks like a continuation of this week’s theme movie, Groundhogs Day. For those getting out into the mountains expect another day of sunny clear skies with relatively mild temperatures (20’s F) above 1000’. Over the last week this inverted weather pattern has been allowing backcountry skiers and riders to push further into the periphery of our forecast zone. In the Turnagain Pass area a mostly LOW avalanche danger exists, but there is still potential to find pockets of unstable snow. These pockets will be more likely in terrain steeper than 40° specifically in places that have had more wind exposure to create a slab 8-10" thick on top of weak snow. 

Old Wind Slabs

A few days ago two skiers triggered an isolated pocket of surface snow while boot packing up a steep Eastern convexity in the Seattle Creek drainage at about 2400’. This isn’t too surprising due to the fact much of the surface snow, top 3-6”, has been loosing strength over the last two weeks due to clear skies and cool temperatures. At mid elevations, below 3000’ a crust layer sits below this weak “faceted” snow creating the perfect environment for localized winds to form a slightly denser slab above. Pay attention to the consistency of the surface snow. If you find yourself in snow where the surface is stiff on top or feels hollow, watch your slope angles. 

At higher elevations above 4000’ a crust/facet combo has been found in thinner areas of the snowpack. This weak layer/bed surface combination showed potential to propagate a slab 10–12” thick in a test pit near the Girdwood Valley. Be extra careful in steep terrain around rocks or convex terrain features where the snowpack is thinner. 

Loose Snow

Cold temperatures and clear skies have continued to make much of the surface snow weak and poorly bonded. In general this is a low hazard, but if riding or skiing on slopes steeper than 40° pay attention. Loose snow with enough volume and momentum can knock you off your feet.

 

Recent sluffing from ski tracks on a Northern aspect where the surface snow is weak and poorly bonded.  

Sun Exposure

Believe it or not the sun has had enough radiation to affect the surface snow on Southern aspects. Several days ago this produced some small damp loose-snow avalanches, but cold evening temps have strengthened this into a crust leaving a thin breakable layer behind. Today the sun warrants an additional concern for any fair skinned creatures such as myself. Sunglasses and sunscreen might be a good idea while clear skies continue throughout the week.


Mountain Weather

Near sea level yesterday’s inverted air kept temperatures slightly cooler (teens F) under a low valley fog.  Above 1000’ temperatures were in the low 20’sF with relatively calm winds. Inland, near Summit Lake, temperatures were in the single digits on shaded areas of the valley floor. No new precipitation has been recorded for the last four days.

Today looks very similar with sunny skies and dense patches of valley fog near sea level. Temperatures look to remain warmer during the day (teens to low 20’s F) but dropping into single digits into the evening. Light winds out of the Northwest are expected at higher elevations.  

Expect more clear, dry, cold weather throughout the week. There has been some discussion about the high pressure over Alaska’s interior combining with a low pressure in the Southeast Gulf creating a tighter pressure gradient later in the week. In other words we could be feeling colder temperatures and strong Northwest winds in Southcentral Alaska near the end of the week. 



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 20  32 
Summit Lake (1400')
Alyeska Mid (1700') 20  20 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 21  10 
Seattle Ridge(2400') 20  Var. 

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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