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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Friday, February 1st 2013
Created: Feb 1st 6:09 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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Rossignol
The Bottom Line

The avalanche hazard remains MODERATE at and above treeline, where winds will create new slabs that will be sensitive to human triggers today.  There also remains a possibility for deep slab avalanches to occur above treeline.  The hazard below treeline is LOW today where it is unlikely for avalanches to occur.


Primary Concern

Wind Slabs

Light density snow that fell early yesterday morning is now being transported to form new wind slabs.  Ridgetop winds picked up overnight and are now creating slabs up to a foot in depth.  The underlying bed surfaces supporting these wind slabs vary depending on elevation.  Between 1,000 and ~2,500' these wind slabs are resting on a slick bed surface, formed by the warm temps of last week and the frigid temps of last weekend/early part of this week.  Expect to encounter the most sensitive slabs at the upper end of this elevation band, especially in open areas where the wind is blowing.  In the upper elevations wind slabs will also form and become sensitive today.  In addition, older pockets of wind slab that can cause problems are still out there as reported by a party on Magnum yesterday.

Loose snow avalanches

In wind sheltered areas above treeline expect to encounter loose snow avalanches running in steep terrain today.  While these avalanches are low in volume, the consequences increase if you're swept off your feet or machine and into terrain traps such as cliffs, trees, and gullies.


Secondary Concern

Deep slabs continue to be a concern.  Weak snow that formed early in the season persists beneath dense snow that fell over the holidays.  We have seen evidence of this problem diminishing greatly below 2,000'.  Above ~2,000' the weak base to the snowpack is still showing the ability to propagate across slopes and create large avalanches.  The reality is that it is very hard to initiate one of these avalanches.  The overlying slab is relatively strong and those weak layers have had time to adjust to the weight of the slabs sitting on them.  While it may seem that there are no problems on the surface, it is important to know the weather history of this season and realize that the weak snow is still there and capable of creating unsurvivable avalanches.


Mountain Weather

A relatively calm and mild day yesterday in the mountains with no precip has given way to increasing winds overnight.  Temps are in the mid to upper twenties at ridgetops and winds are currently blowing 20 mph out of the East and Southeast with gusts to 30 mph.

Expect increasing clouds today with temps remaining mild, in the mid twenties to near 30 F at ridgetops.  Winds will be out of the E and SE at 15-20mph.  Snow showers should begin this evening and continue into tomorrow.

The extended outlook calls for a continuation of unsettled weather, with snowfall amounts remaining light and temps staying mild.

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Kevin will issue the next advisory tomorrow morning, February 2nd.

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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