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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Friday, February 26th 2016
Created: Feb 26th 4:17 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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We received an observation yesterday about recent avalanche activity on the trail to the Barber Cabin near Cooper Landing. It is worth a look and is a good reminder that summer trails may cross large avalanche paths. Click HERE to read the observation. 

 


The Bottom Line

The avalanche danger in the Treeline and Alpine elevation bands is CONSIDERABLE today. This means human triggered avalanches are likely on slopes 30 degrees and steeper and natural avalanches are still possible. Cornices are huge, glide cracks are releasing and wet snow is a concern. Elevated caution is recommended. Very cautious route finding and conservative decision-making are important if venturing into the mountains today. Watch for changing conditions this afternoon as the next storm intensifies. 

The danger is MODERATE below 1,000' where debris from an avalanche above may run into channeled terrain.

Dangerous avalanche conditions also exist in the Summit Lake area. See Saturday's Summit Lake Summary and click HERE for recent observations from the last few days.


Primary Concern

After a brief period of clearing yesterday the clouds rolled back in and light snow and rain fell overnight. Today is forecasted to be cloudy with rain and snow showers and the wind and precipitation is forecasted to pick up tonight. What this means is there is a bit of a lull in major loading of the snowpack but there is still a lot of uncertainty about the set-up. We have received a lot of snow and rain (in a short period of time) and had strong winds. Warm temperatures have increased the likelihood that the storm layers are bonding but this has increased the chances for wet avalanches (see below). We have very limited information on the snowpack in the Alpine. There are a variety of concerns for today. This all means a conservative mindset is important. 

Storm Slabs: Fluctuating temperatures and snowfall may combine to create storm slabs as new layers of snow are deposited. Pay attention to how well the new snow bonds to the snow below. 

Wind Slabs: Winds today will continue to add stress to very large wind slabs in leeward terrain. Human triggering of these could be very dangerous due to the depth of slab. Avoid steep wind-loaded slopes. 

Cornices: Natural cornice fall activity is still possible today and could trigger an avalanche on the slope below. Again this something you want to avoid traveling on or underneath. Cornices will be tender and could break way farther back than expected. Falling down the slope with a refrigerator to school bus sized chunk of snow on your snowmachine or skis would be terrible, if not deadly.


Secondary Concern

The storm that ended yesterday brought rain up to almost 1800' that fell on to 1-2' of snow. Temperatures remain around freezing or above at lower elevations. Rain is forecasted to fall again today up to 1600'.  All this has created a set-up that is prime for wet avalanches. Natural wet loose and wet slab avalanches will be possible in the mid elevation band today and human triggered avalanches are likely in steep terrain. Look for roller ball activity, that is an indication that the surface snow is loosing strength and avoid terrain traps. Wet snow can be very hazardous especially if it gets moving and stuffs you into bad spot.

 

Recent wet slab avalanche South of the Bertha Creek campground.

 


Additional Concern

Well... another glide avalanche happened! It was easy to check it out while getting gas at the Girdwood Tesoro. This is a great reminder that many glide cracks are still lurking under the new snow and have the potential to release at any time. Glides threaten a lot of well-traveled terrain on both the motorized and non-motorized side of the highway. Observers also reported that some of glide cracks are reappearing that indicates they are on the move. Avoid travel below glide cracks or under terrain where they might be.

 

Glide avalanche on the West face of Pyramid Peak. This happened sometime before 10:30 am when we first received a report of it.


Mountain Weather

The intense storm moved out yesterday and there was a brief window of clearing before the clouds and precipitation moved in again bringing rain and snow showers. Temperatures were above freezing for most day at lower elevations and in the mid to high 20Fs above 3000'. Easterly winds were moderate 25-35 mph with some gusts in the 50s. 

Today will be mostly cloudy with continued rain and snow showers. Rain/snow line is forecasted to be around 1600'. 0-5" of snow could fall at higher elevations. Winds will Easterly 20-40 mph. Temperatures will be in the 30Fs and 40Fs. Precipitation and winds will pick up overnight. 

This pattern continues into the weekend with warm temperatures, rain and snow and Easterly winds. Southcentral is in a 'warm southeast flow'. Lows continue to move into the Gulf and moisture will continue to push into the advisory area. 

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  34 .6  134 
Summit Lake (1400')  35 0 42 
Alyeska Mid (1700')  33 1 .14  104 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  ENE  25  67 
Seattle Ridge(2400') 27   n/a n/a  n/a 

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 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
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: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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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