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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Monday, February 27th 2012
Created: Feb 27th 7:00 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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The Bottom Line
Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Monday, February 27th at 7am. This will serve as 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).


ANNOUNCEMENTS
Alaska DOT crews will be conducting avalanche mitigation work along the Seward Highway. Intermittent road closures are possible - check 511.alaska.gov for more information.


BOTTOM LINE
The avalanche danger remains CONSIDERABLE for storm snow instabilities with continued snowfall. Dangerous wind slab avalanches are likely to be triggered on steep slopes with recent wind deposited snow above treeline. Additionally, loose snow avalanches will be likely and soft slab avalanches will be possible to trigger at all elevations on slopes greater than 35 degrees. Conservative travel is recommended today.

AVALANCHE DISCUSSION
By yesterday afternoon, Sundays storm had laid down 8-14 inches of new snow with moderate to strong easterly winds. As of this morning, the wind has decreased but snow is still falling. Storm totals are now hovering between 1 and 2 feet slightly more in the Girdwood Valley and less at Summit Lake. The extent of natural avalanche activity yesterday was shrouded in the clouds, as usual, but people were able to trigger pockets of fresh wind slabs on steep rollovers near treeline.

The new snow came in on top of several inches of very loose powder containing large sharp crystals and initial bonding was poor (further details and video HERE). Along with the poor bonding, increasing temperatures and/or wind allowed the new snow to become cohesive and act as a slab. This weak snow under the new slab made for easy cracking and small avalanches on steep short test slopes near and below treeline. It is a fairly easy bet that areas above treeline, with significantly more wind, were quite sensitive.

Today this bonding with the old snow, as well within the new snow from overnight, is the big question. It is likely settling out and slabs will not be as easy to trigger at and below treeline. There, of course, is uncertainty with how quickly the increase in stability will be above treeline.

Above treeline:
Wind slabs that are sitting on loose weak snow is todays primary concern. The winds have died down dramatically this morning but light snow continues which can cover the visual clues as to where they lie. Conservative travel above treeline (e.g., keeping slope angles low) is recommended today as these slabs may be strong enough to allow a person to get well onto the slope before it releases making escape difficult and consequences unpleasant.

All elevations:
Loose snow avalanches are expected to be easy to initiate with the continued new snow. As is the key with these, keep an eye on where your sluff runs. It may also be possible that these sluffs could pull out a wind slab lurking below.
Soft slab avalanches may be less likely today but still possible to trigger on steeper rollovers in areas without much wind. These could fail both on the older snow creating a deeper avalanche, or within a change in density within the new snow for a shallower avalanche.

Cornices continue to grow and teeter on the brink of failure. Check out the updated pictures and observation sent in yesterday.


MOUNTAIN WEATHER
The storm that rolled through yesterday laid down a healthy dose of medium density snow. As of this morning, estimated totals are:
Turnagain Pass are 14-20"
Girdwood Valley 20-25"
Summit Lake 8-12"

Easterly winds accompanied the new snow and averaged around 35mph with gusts up to 60mph. The wind has shifted early this morning and has died down where it should remain light from a northerly direction. Light snow will continue to fall through the day adding anCNFAIC Staff 3-5 inches (with possibly more) of lower density snow. Temperatures warmed through the storm yesterday but have begun a slight decrease this morning where they sit at the mid 20s at 2000 and the upper teens at 4000.

CNFAIC Weather Page and the NWS forecast

Graham will issue the next advisory Tuesday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.

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

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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