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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, April 2nd 2015
Created: Apr 2nd 5:24 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'
 Show the Complete North American Avalanche Danger Scale
Alyeska Resort
The Bottom Line

The avalanche danger is MODERATE today above treeline.  Human triggered avalanches 2-3’ deep are possible in isolated areas, particularly North facing terrain.  This looks to be the first day in a week without some measurable precipitation so it’ll be important to let the snowpack continue to adjust to this recent load.  Keep your terrain choices conservative today and as always, practice safe travel protocol when moving through the mountains.

Other concerns today include the impending cornice hazard and wet loose avalanches; both of which may be influenced by a warm Spring day on tap.

Below 2500’, the danger is LOW though potential exists for an avalanche or cornice initiated in the alpine to run into this elevation band.


Primary Concern

Many observations over the last week have pointed toward a strengthening snowpack in the core advisory area.  The exception to this appears to be North aspects above treeline as we’ve had reports of large avalanches in these areas over the last two days; most recently yesterday a skier triggered an avalanche and went for a 1,000’ ride on the north side of Magnum.  Let's not forget that we have seen 3-5 feet of snow in the alpine (consolidated to 2-3 feet) over the last week that fell on a myriad of different surfaces.  Upper elevation north aspects are notorious for harboring weaker snow longer, which is exactly where surface conditions are best, but also where unstable snow is being found.  Recognize that if an avalanche is initiated, it will likely be big and encompass at least the last week’s storm (2-3’) with the potential to step down deeper. 

As days grow longer (gaining 5 min 44sec today!) and sunnier, the temptation to ski bigger lines and push further out from the road and into periphery areas is strong.  With this, safe travel protocols become increasingly important.  Expose only one person at a time on a slope and utilize good communication and true islands of safety.  


Secondary Concern

Defying gravity seems an accurate term for some cornices right now.  Given the last seven days of sticky snow and moderate ridgetop winds many of these have grown to full-curl.  Some have failed (Pyramid West face and Todd’s run) but many have only grown closer to the breaking point.  This is a much simpler problem than the aforementioned persistent slab because we can see cornices; and what we can see, we can avoid.  Simply minimize time spent underneath and give these backcountry bombs an extra wide berth when travelling on ridgelines.  

Hippy bowl ridge and large, curling cornice.


Additional Concern

Daytime heating and light winds could be concern for wet loose avalanches on steep south and west facing slopes today.  Generally slow moving, these are a different beast than a slab avalanche.  Wet loose activity is generally of concern if the potential exists to push you off your skis and into a terrain trap.


Mountain Weather

Yesterday morning started out with an intense band of snow moving through Turnagain pass depositing a quick 2-4” at the road.  Temperatures warmed throughout the day and intermittent periods of sun through broken clouds proved enough to melt that little bit of accumulation by 5pm.  On ridgetops, temps were in the mid 20’s, winds light to moderate from the northeast and intermittent snow showers added up to 3-5” (above 2,000’) on the northern side of Turnagain pass.

Today looks to be the start of a clearing trend that will last through the weekend with no precipitation forecasted.  Expect temps to be warm today (mid-30’s at 3,000’) and wind shifting to the north in the 10-20mph range as an outflow (off shore winds) regime sets up.  Slightly cooler air will filter in tomorrow and through the weekend under clear skies.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32  2  .2 59 
Summit Lake (1400')  35  0  .04  10
Alyeska Mid (1700')  33  2  .15  36

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23   ENE 11  38 
Seattle Ridge(2400') 26   n/a 10  29 

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: Nov 18, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to 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.


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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