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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Saturday, December 13th 2014
Created: Dec 13th 6:30 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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 LOW in the treeline and alpine elevations.  New snow arriving today will not be quite enough (3-5”) to bump up the danger except for in isolated pockets on steep upper elevation leeward slopes.  On these terrain features the avalanche danger will be MODERATE; expect small pockets of slab up to 6” deep to be very sensitive to human triggers and low in volume.

Below treeline, between sea level and 1,500’, there is little to no snow on the ground and no danger rating.

Firm snow surfaces between 1,500'-2,500’ require careful travel today.  Early season hazards such as stumps, rocks and open water will begin to be covered with a thin layer of snow.  Pay attention to these obstacles in these areas in order to avoid injury.


Primary Concern

It has now been 5 days since the last precipitation fell.  During this past week temperatures have cooled and allowed a once rain soaked surface to refreeze between 1,500'-2,500’.  As you might guess the snow surface in this elevation band is firm to say the least.  “Boilerplate” and “coral reef” are terms that come to mind when thinking about this rain crust.  Once above this elevation band, you will find enjoyable and mostly stable snow.  Significant slope tests in the form of cornices were witnessed on Thursday with minimal avalanche activity.  A lack of buried persistent weak layers in the snowpack in the higher elevations has allowed instability to be confined to during and immediately after this most recent (now not so recent) storm.

New snow amounts today will be in the 3-5” range and are not enough to create slabs big enough to be of concern.  You may find exceptions to this on steep wind loaded slopes in the higher elevations.  Paying attention to areas that are receiving enough snow and wind to build slabs over 6” will be important today.  Keep in mind that these areas will be few and far between.  Volume of any potential slabs today should be very low.  Any new snow falling today will be touching down on a layer of surface hoar in many areas and consequentially will be sensitive to human triggers.

Other hazards in the mountains today will be traveling in the mid elevations on firm surfaces (hint: sharpen your edges), exposed rocks, stumps, and open water.


Additional Concern

We are tracking several areas in the forecast zone that have glide avalanches.  Tincan trees, Eddies, and the East face of Pyramid all have glide avalanches of varying size.  No new movement was observed yesterday.  As always steer clear of any open cracks you see on the snow surface.  These avalanches are moving in super slow motion but could change speed without the normal warning signs that we typically associate with avalanche release.


Mountain Weather

Over the past 24 hours no new snow has fallen in the forecast area.  Winds have been light out of the East.  Temperatures have averaged in the mid 20s F at ridge tops.

Today expect light snow to begin by midday.  Accumulations look to be light, in the 3-5” range.  Winds will be out of the Southeast at 15 to 25 mph.  Temperatures will be just below freezing (32F) at 1,000'.

The extended outlook is calling for continued snow showers overnight and through the rest of the weekend.  The most intense precipitation should arrive tonight with another dose coming Sunday night.  Temperatures over the next few days look to fluctuate and warm enough for rain/snow line to climb into the 1,000'-2,000' range.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 26  0  0  18
Summit Lake (1400') 17  0  0  4
Alyeska Mid (1700') 27  0  0  12.4

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 22  E  10  21
Seattle Ridge(2400') 25  ENE  8  25

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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