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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Saturday, February 1st 2014
Created: Feb 1st 6:28 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 danger is MODERATE above treeline for deep slab and wind slab avalanches. At elevations above 3,000', weak snow sits underneath a dense slab 3-6+' thick creating the potential for a human triggered full-depth avalanche. The likelihood of triggering a deep slab is low but the consequences are high as these can be large and destructive slides. Also in the upper elevation exposed terrain, be on the lookout for old hard wind slabs or fresh slabs in the 6" range. Below treeline the danger is LOW where triggering an avalanche in unlikely.


Primary Concern

No new avalanche activity has been noted since the end of the warm, wet weather on Tuesday Jan 28th - but Kevin did get some great aerial shots of old avalanches from the Jan 17-27 cycle yesterday. There have been only a few folks getting out lately. I'm guessing this is due to the challenging travel conditions, which consist of negotiating a hard surface crust that extends up to 3,000'. Though the sun has been out it has not been able to soften the crust. There may be a few exceptions on steep southerly slopes receiving little wind and direct sun.

Snowpack below 3,000':
The recent cold temperatures are freezing the snowpack more and more every day. There is still wet snow at the bottom of the pack but this continues to drain. The crust that was over a foot thick is getting thicker.

Snowpack above 3,000':
This is where the deep slab primary concern comes into play. Though it has been a week since the last known deep slab avalanche (Goat Mtn in Girdwood Valley), it is still on our radar. This is simply because we know faceted snow exists under 3-6+' of dense slab. A few ways of handling this problem is either to steer clear of steep slopes (35 degrees or steeper) at the upper elevations or hedge your bets by only exposing one person at a time. If the later is chosen, look for the safest 'relative safe spot' you can find to watch your buddy. If a deep slab is triggered it could run much further and propagate wider than expected. Lastly, be aware of shallow areas in the slab that can be trigger points - for example, rocks and the tops of rollovers.


Secondary Concern

Above 3,000' the surface crust transitions to 4-6" of soft wind affected snow over a dense base. Many exposed areas have been stripped by the wind and pockets of hard wind slab are scattered in catchment zones and the lee sides of ridges. If you are traveling in these upper elevations harboring dry snow, be on the lookout for older stiff wind slabs as well as any recent wind deposited snow. There is limited loose snow available for transport and I'd expect any fresh slabs to be mostly shallow (in the 6" range or less). As always, be aware of any cracking in the snow around you.


Additional Concern

With many days of unseasonably warm weather during January, some of us are wondering just where did we stack up in the monthly averages. There is more data to crunch so stay tuned - but we do have a few sets of interesting numbers. Below are graphs of precipitation, SWE (Snow Water Equivalent) and Temperature. 

 

                               


Mountain Weather

Mostly clear skies and sunshine prevailed again yesterday above the entrenched valley fog along Turnagain Arm. A mild inversion is in place with temperatures during the past 24-hours in the low 20's F at sea level to the upper 20's F on ridgetops. Winds have been light from the Northwest averaging around 10mph.

Today it will be another mild day in the mountains. Skies should be mostly clear with possibly some high clouds and winds light from the Northwest. Temperatures look to stay in the mid 20's F at all elevations. 

The blocking high pressure that has developed over mainland Alaska is expected to persist into next week - bringing us continued clear and cool weather. Models are showing a large low pressure system developing Sunday night through Tuesday south of the Aleutians. At this point, it doesn't look like the low will be strong enough to push through the blocking high, limiting our chance for precipitation.

 

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: Apr 11, 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: OpenWide swaths of open river in the Placer Valley. Travel with extreme caution!
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: ClosedClosed for the remainder of the 2017 season.
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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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