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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, January 27th 2013
Created: Jan 27th 6:39 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 Libby Group
The Bottom Line

A MODERATE danger continues above treeline for wind slab and deep slab avalanches. Northwest winds will continue to form wind slabs on leeward slopes that will be possible for a person to trigger today. These will be most likely found in the steeper terrain and in cross-loaded gullies and sub-ridges. Additionally, there remains the possibility of triggering a deeper and more dangerous avalanche, most pronounced on steep slopes with a shallow snow cover. There is a LOW danger below treeline where a stout crust exists on the surface.


Primary Concern

Yesterday, the cold and sustained NW wind not only affected the ridgetops but also penetrated down to treeline in some locations. This allowed for wind slabs to form both on and off the ridgelines. These were on various aspects as the wind was being channeled in many directions by the terrain. A few of these 6-12" slabs were triggered yesterday by people but were confined to the steeper terrain (around 40 degrees or more).

Today we should see more the same. The cold NW wind continues and though there will be less snow available for transport, we should still see shallow slabs forming. Most of these are likely to be a bit sluggish on slopes around 35 degrees but in steeper terrain expect them to release and pack more of a punch. These slabs can become quite serious in committing terrain if, for example, one gets dragged over a cliff or caught and covered in a terrain trap. Watching for current wind loading, stiff or hollow feeling snow that may crack around you will be signs you have found a wind slab. Also, watch for cross-loading in gullies and sub-ridges as these winds have been blowing well below the ridgetops during the past 24 hours.

As far as the snow surface conditions go, they are highly variable with significant wind affect at most elevations. Soft powder can still be found among the wind hardened surfaces in the more sheltered locations above 2,000’. Mostly supportable crusty conditions exist below 2,000’.


Secondary Concern

The deep freeze over us again today is helping considerably to “lock” in the snowpack as a whole (except for the wind slab problem discussed above). However, we are still concerned that in shallow areas above treeline there remains a chance a person could trigger a slab avalanche breaking near the ground. Keeping with good travel practices – exposing only one person at a time, moving efficiently through steep terrain and steering clear of trigger points such as shallow areas near rocks will be your best bet for avoiding one of these larger and more dangerous slides.

 


Mountain Weather

If you thought yesterday was a cold one, just wait for today... We have fallen - literally - off the charts for temperature at many ridgetop locations. Our Friends weather stations are reporting near or below -10F at all locations this morning while lower elevations are slightly warmer in the -5 to +5 range. Temperature will continue to decrease another few degrees over the course of the day.  But, skies are clear and the sun will be out!  Wind? It was in the bothersome range on the ridgelines yesterday (NW @ 10mph gusting 25mph) and has picked up slightly this morning (predominantly NW @ ~15mph gusting 35mph). Good frostbite weather.

Tomorrow temperatures should bounce back to a more civilized range as winds shift back to the SE bringing clouds and warmer air ahead of a large low pressure system pushing into the Gulf. Snow flurries are in the forecast for Monday night into Tuesday with a better chance for accumulation on Wednesday.

 


Fitz will issue our next advisory tomorrow morning, January 28th.

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.


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