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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Friday, February 15th 2013
Created: Feb 15th 6:06 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.
 Show the Complete North American Avalanche Danger Scale
Special Announcement

AK DOT will be conducting avalanche hazard reduction work today on the Seward Highway between 9:15AM and 11:00AM between Girdwood and Portage (MP88-83). Motorists should expect delays up to 45 minutes. Updates can be found at 511.alaska.gov.

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Stop by the motorized lot this morning at 11AM! Join CNFAIC forecasters and Gold Level sponsor Alaska Mining and Diving Supply (local Ski-Doo dealer) for an avalanche awareness event and memorial snowmachine ride on the 5th anniversary of this fatal avalanche in Turnagain pass.
http://www.cnfaic.org/accidents/avy021508.htm


The Bottom Line

The avalanche hazard is CONSIDERABLE above treeline where over a foot of new snow and winds have created dangerous slabs that will be easily triggered today.  Below treeline the hazard is MODERATE, where isolated pockets of wind slab and storm snow will be possible for skiers and snowmachines to trigger.


Primary Concern

Intense snowfall combined with strong winds in the early part of the day yesterday have created new slabs 2-3' in depth.  Expect these slabs to be sensitive to the weight of a person or snowmachine today.  While some time has allowed the underlying snow to adjust to this new load, there is enough new snow, especially in wind loaded terrain to warrant concern.  These slabs are large enough on their own to injure or bury a person.  At the mid elevations, there is the possibility of these slabs to step down to older layers of weak snow.  Be on the lookout for shooting cracks, collapsing/whoompfing and snow that has a hollow feel to it.  Staying off of steep rollovers, starting zones and snow that has a rounded or pillowy look will help in avoiding this problem today. 


Secondary Concern

Snowfall amounts ranged from a few inches at lower elevations to 16" in the higher elevations in the past 24 hours.  Expect these slabs to gradually become less reactive as the day progresses.  These instabilities tend to heal quickly.  However, an additional 4 inches of snow today will keep this problem lingering through the day.  Expect storm snow to release in terrain over 35 degrees as we experienced yesterday.  This problem will be more apparent and pronounced as you gain in elevation, particularly where new snow amounts exceed 10".

 

 

 

Additional Concerns
Persistent Slabs

A crust that formed in the latter part of January has shown up as a problem in certain areas in our region in the past week.  A thin layer of weak snow between this crust and 2-3 feet of snow is the interface that concerns us most.  This crust is most pronounced between 1,800-2,400'.  This problem is not as geographically widespread as our primary concerns.  When traveling within this elevation band today steer away from slopes over 35 degrees, as avalanches in the new snow have the potential to step down to these older layers of weak snow.  

Cornices

Cornices have significantly gained in mass over the last 24 hours.  Keep your distance from cornices today.  They will likely be sensitive to the weight of a person or snowmachine.


Mountain Weather

The mountains around Turnagain Arm have picked up 16" inches of snow with 1" of water in the higher elevations over the past 24 hours.  Winds averaged 30mph out of the East in the morning yesterday and temps were moderate, averaging in the low 20s at 3,800'.  Snowfall was most intense during the late morning/early afternoon yesterday.

Lingering snow showers are continuing to put down light amounts of snow around the area.  Winds calmed down in the afternoon yesterday and are currently averaging 2mph out of the West at the Sunburst weather station.  Temps are currently 20 degrees F at ridgetops and around 32 F at sea level.

Today lingering snow showers should produce up to 2-4 inches of accumulation.  Ridgetop winds will blow out of the West at 5-20mph and temperatures at 1,000 feet will be in the high 20s.

Tomorrow we should see clearing skies as a small ridge between low pressure systems moves through the area.

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Wendy will issue the next advisory tomorrow morning, February 16th.

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

Subscribe to the Turnagain Area Avalanche Advisory:

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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