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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Saturday, April 13th 2013
Created: Apr 13th 5:16 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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The Bottom Line

The avalanche hazard is LOW in many areas.  Shallow wind slabs up to a foot in depth and loose snow avalanches will be easy to trigger in upper elevation starting zones.  In these areas the avalanche hazard is MODERATE today.


Primary Concern

We have received reports of several human triggered wind slabs over the last several days.  Yesterday my partner and I were able to release one of these slabs on a steep rollover on a west facing slope, as pictured below:


Lipps 4-13

Expect more of the same today.  The warm temps of last week helped to form stout crusts on all but north facing upper elevation slopes.  Since that time we have seen less than a foot of new snow accumulation on Turnagain Pass and closer to a foot around Girdwood.  The last three days of clear and cold weather has helped to weaken the snow, particularly at the interface between these crusts and whatever new snow has fallen over the past ten days.  In areas that received wind loading in the last several days these shallow slabs will be sensitive to the weight of a person today.


Secondary Concern

Areas that have been sheltered from the wind are holding very weak loose snow.  We were able to easily trigger sluffs in terrain over 40 degrees yesterday.  Sluffs were relatively low in volume but were running long distances.  With this in mind, it will be important to manage your sluffs today.  The bigger and steeper the terrain, the greater the volume these sluffs will become. Don't let your sluff catch up with you; turn away from moving snow, let it go past you or move faster than it to manage this problem.

With clear skies and just slightly warmer temperatures in store today, pay attention to steep slopes receiving direct sun.  There is potential for shallow damp loose snow avalanches to release naturally later in the day. 


Mountain Weather

In the past 24 hours the mountains around Eastern Turnagain Arm have received no precipitation.  Winds have been blowing 7mph out of the NW with gusts to 23mph at the Sunburst weather station (3,812').  Winds were stronger in certain higher elevation locations that were catching the north winds yesterday as we observed in both the Turnagain and Summit Lake areas (see photo below).  Temperatures at Sunburst have averaged 6.8 degrees F.

Summit Wind loading 4-13

Look for today to be very similar to yesterday.  Light to moderate winds, blowing less than 10mph out of the North may help to move around any snow available for transport.  Clear skies will help to heat up sun exposed slopes later in the day.  Temperatures at 1,000' will climb into the mid to high 20s F.

A ridge of high pressure has established itself over the Bering Sea and is extending into our area.  This will translate to clear skies through the weekend with temperatures rising just slightly over the next few days.  Look for winds out of the north to pick up speed tomorrow.

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Wendy will issue the next advisory tomorrow morning, April 14th.

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
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