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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Thursday, March 21st 2013
Created: Mar 21st 6:24 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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Alaska Mountaineering and Hiking
The Bottom Line

The danger rating is higher today, bumped to MODERATE above treeline for fresh reactive wind slabs found yesterday.  We had a number of reports of people finding stiff pockets that popped from the weight of a skier, in some cases causing the skier to go for a ride. 

Besides wind slab, cornices are still a problem and have produced the largest avalanche events we've seen the last week.  Loose snow is harder to find since the wind picked up, but some areas may still produce localized sluffing in steep terrain.


Primary Concern

The wind picked up 2 nights ago with ridgetop stations reading sustained northwest wind to the 20s and gusts over 50mph in some places.  This was enough to produce specific areas of wind slab that can be triggered by a person.  Yesterday we found a small mid slope pocket that collapsed a ~30 foot section with shooting cracks within the 2-5 inch thick stiff wind slab.  Other people reported more serious occurances yesterday including one person who took a 250-300 foot ride. 

Keep in mind that this problem is confined to the surface, meaning it will not step down into deeper layers given the current stability of the snowpack.  However, in terrain with consequences it could be enough to be a hazard if caught off guard. 


Secondary Concern

With increased wind we also get increased stress placed on the cornices as they gain mass.  Below is a picture from the Summit Lake region that shows a good example of a large cornice failure.  Also note the pocket of wind slab to the right that doesn't appear to be directly connected to the section of cornice failure. 

 


Mountain Weather

Cold temperatures and clear skies continue this morning.  Wind has been moderate to strong for the past 36 hours from the northwest. 

Today is the last day of sun in the short-term forecast.  We can expect clouds to build throughout the day.  By tonight snow is back in the forecast, with 2-5 inches predicted.  The storm track is from the west, which is not the typical direction for Turnagain Arm to receive a lot of precipitation.  At this time the weather service is predicting more snow for the Matanuska and Susitna valleys. 

For long term stability, we can expect a dramatic decrease in stability with new snow in the forecast.  Our current snow surface is mostly near surface facets or sun crust, both of which do not allow for quick bonding of new snow. 


Fitz will issue the next advisory tomorrow morning, March 22nd.

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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