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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, February 7th 2013
Created: Feb 7th 6:58 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.
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Special Announcement

We have a few spots open in our non-motorized backcountry observer training day this Saturday, February 9th.  Check our calendar page for more information.  Join the forecasters for a day in the backcountry and learn how to contribute snow and avalanche observations to your local avalanche center.


The Bottom Line

An active storm will bring the first marked bump in our avalanche danger in two weeks.  The avalanche hazard is CONSISERABLE above tree line and MODERATE below tree line by way of a winter storm moving into the forecast area.  As this storm progresses throughout the day, we can expect stability to decrease while moderate to strong winds actively build fresh and very tender wind slabs.  Natural avalanches will be possible and human triggered avalanches likely in specific terrain.  A BLIZZARD WARNING remains in effect for Portage Valley and eastern Turnagain Arm from 10 AM to 6 PM today.


Primary Concern

Forecasted 40-55 mph east winds are guaranteed to build very tender and sensitive wind slabs with yesterday’s 4-8” of light powder combined with today’s storm snow.  As you gain in elevation, slabs will be actively forming throughout the day on a variety of bed surfaces including breakable crusts, buried surface hoar (observed on Tuesday in Girdwood and Turnagain) and in the upper elevations older wind slab.

Below tree line where winds are not as intense, avalanche size is likely to be small though human triggered avalanches will be possible.  Slabs will form mostly on a breakable crust at these lower elevations. 

Above tree line expect slabs to form in all the usual places; below ridgelines on west-facing (leeward) slopes and cross-loaded gullies.  With moderate to high winds, slopes tend to load further downhill than one would think, often luring a skier or snowmachiner mid-slope before finding the trigger point.  The likelihood of triggering a slab in terrain greater than 35 degrees today is probable; there is however some uncertainty on just how big an avalanche may be.

As a fresh shot of wind and moisture rolls in today it is worth mentioning that at higher elevations there still exists weak, faceted snow at the bottom of our pack.  Though we have not seen an avalanche fail on this layer in several weeks, deep slab instabilities are notorious for lying dormant for long periods only to suddenly awake and catch us off guard.  At this point, safe travel protocol will be your best bet to avoid this avalanche concern.


Secondary Concern

If you happen to find areas sheltered from the wind today, yesterday’s low-density powder combined with storm snow will create fast-moving loose snow sluffs in steep terrain.  If expected, these loose-snow slides should prove quite manageable.


Mountain Weather

Well it looks to be a bonafide storm day in the eastern Turnagain Arm region today.  Expect this system to ramp up throughout the daylight hours bringing 8-16” of snow (at all elevations!) and 40-55 mph winds from the east.  Temps look to be in the mid to high 20’s at 1000’ and should stay below freezing at sea level.  A BLIZZARD WARNING remains in effect today from 10 AM to 6 PM.

Tomorrow looks to be a break in action before another weather front moves into south-central over the weekend.  This next system looks promising for more wind and precipitation.


Fitz will issue the next advisory tomorrow morning, February 8th.


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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