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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Friday, December 14th 2012
Created: Dec 14th 6:55 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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The Bottom Line

BOTTOM LINE

A CONSIDERABLE avalanche danger continues above treeline today. Weak faceted snow underneath the new snow from Saturday and Wednesday produced both natural and human triggered avalanche activity yesterday (see below). Today, the natural activity can be expected to diminish but human triggered avalanches are still likely. Most prone areas are slopes steeper than 35 degrees in areas with wind deposited snow or areas just out of the wind affected snow and sporting good riding conditions. Below treeline there is a MODERATE danger of triggering a slab on these steeper slopes.

Remember your good travel practices. Only exposing one person at a time, keeping a close eye on your partners and discussing potential avalanche areas/consequences will be prudent.


Primary Concern

Widespread natural avalanche activity was seen on the east face of Seattle Ridge yesterday – releasing sometime in the morning hours. These slopes were loaded by moderate westerly winds, not associated with snowfall, that shifted from the predominant easterly flow Wednesday night through last night. This is the first significant avalanche activity seen on east aspects.

Today, a shift back to west winds, increasing to 30mph by this evening, may not be enough for fresh slabs to develop during the daylight hours, but any slabs from the past several days are still VERY suspect for human triggering as they are sitting on weak faceted snow. Especially concerning in areas that have not seen much traffic.


Secondary Concern

If one remembers back a week ago to the end of our period of cold and clear weather then you’ll remember how weak the surface snow was then. So weak it would easily sluff down the slope without much effort. This was the result of extensive faceting under clear and cold conditions that created what we are now calling the November facets. We have now added ~16” of snow from two storms on top of these weak facets resulting in easy natural and human triggered avalanches. The tenuous nature of the weak layer reared its head yesterday with the significant natural activity on E Seattle Ridge mentioned above.

Yet, even areas out of the wind affected snow are concerning. Our party yesterday easily triggered a small slope, just out of the wind, that failed in the November facets and kept us off any larger steeper slopes. Collapsing is still prevalent, and other than recent avalanches is your best clue to unstable snow - this has been keeping many people off the steeper and more committing terrain. That said, the riding conditions are quite improved and good terrain management can make for a great day in the backcounty.


Mountain Weather

The westerly winds that kept ridgetops chilly and avalanche activity present yesterday have shifted back to the east overnight where they have been light. Today they swing back to the west again and pick up to the 25-30mph range by this evening. Temperatures should remain in the teens today with mostly clear skies.

Saturday, very cold air moves in with a good push from a northwesterly flow and temperatures should drop significantly – back to the minus single and double digits. Our next shot of precip is several days away at best.


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). 

Kevin will issue the next advisory Saturday morning, December 15th.

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: Apr 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
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: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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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