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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, April 5th 2015
Created: Apr 5th 6:16 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.
0 NO RATING Below Treeline / Below 1,000'
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The Bottom Line

The avalanche danger is MODERATE above 2,000' on Northerly aspects for triggering a slab avalanche 2-3' thick. The likelihood for triggering one of these large slides on steep shady slopes is decreasing, but the consequences remain high. Other areas of concern are fresh wind slabs and loose snow avalanches where up to 6" of storm snow accumulates today as well as large and overhanging cornices.


Primary Concern

Although a storm is slowly rolling in today for the early part of the week, we are still concerned about weak snow sitting under a 2-3' slab on Northerly aspects. For the past 5 days we have been investigating a number of buried weak layers that were highly reactive Tuesday through Friday and over the weekend have shown signs of gaining strength. Despite the decreasing possibility of triggering a slab, good travel habits are important to stick to if venturing into the soft snow on Northerly slopes. This means exposing one person at a time, watching your partners, having escape routes planned if the snow moves and have all your rescue gear in working order and know how to use it.


Secondary Concern

Fresh shallow wind slabs and loose snow avalanches may be found today with an expected 2-6" of new snow. Ridgetop winds are forecast to be just strong enough to move the new snow around and build soft slabs anywhere from 4-8" thick. These are not likely to pack much of a punch unless more snow and/or wind develops. In some areas they will be forming on a slick crust and if you find a larger 8" pocket, say, it could run further than expected.

Sluffs in the new snow should be expected on steep slopes (where enough snow accumulates). If steep South slopes warm later in the day, natural wet/damp sluffs will be likely, yet low volume.


Additional Concern

Cornices will continue to deserve respect from now until they are melted out or calved off. It's also important to remember that daytime heating can weaken their roots and increase the likelihood for collapse, natural or human triggered.

Check out the photo from Friday below, yikes. Sadly, Alaska had its third avalanche fatality last week when a cornice broke taking a skier with it. This happened in the Wrangell-St Elias area and while details are currently being gathered, you can see the preliminary write up along with the Nation's other fatalities HERE.

"Things not appearing as they seem" and "Don't follow our tracks!" were the quotes referring to the photo. This was sent in to us from two longtime supporters of the CNFAIC that were skiing the North ridge of Eddies Bowl. See their write up HERE.


Mountain Weather

Yesterday's impending sunny and warm day was cut short with clouds and a cool breeze moving in by the afternoon. High temperatures were around 30F on the ridgetops and 45F at 1,000'. Ridgetop winds were from the East in the 5-15mph range.

Overnight, precipitation has started up in some areas associated with a large low-pressure system in the Bering. This is pushing a warm front in from the Southwest and up Cook inlet (a good set-up for precipitation in Anchorage). Although Turnagain Pass is still dry this morning, the Alyeska Mid station (1,700') has picked up 3" of new snow! We should see an additional 2-4" of snow through the day. Winds will be light to moderate from the South and East, 10-15mph. Temperatures in the mid-20's F on the ridgelines and low 30's F at 1,000'. We should see snow to, or very close to, sea level.

Monday and Tuesday the bulk of the precipitation and stormy weather is expected to hit us. Temperatures look to warm enough for rain as high as 1,000', possibly higher, and precipitation amounts are in the .5-1" of water range by Tuesday evening. Stay tuned.

 

PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 34  58 
Summit Lake (1400') 33  0 10 
Alyeska Mid (1700') 35  0.25  33 

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  26 
Seattle Ridge(2400') 27  n/a  10   35

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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