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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Friday, March 17th 2017
Created: Mar 17th 5:41 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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
Special Announcement

Consider showing your support for public avalanche centers when applying for your 2017 PFD!! Friends of the Chugach National Forest Avalanche Center is an official Pick. Click. Give. organization!


The Bottom Line

A LOW avalanche danger remains in the backcountry at all elevations. Although triggering an avalanche is unlikely, it is not impossible on steep wind loaded features and in extreme terrain. Be aware of old hard wind slabs and fast moving ‘sluff’ in steep terrain where getting knocked over could have high consequences. Cornices and glide cracks exist in some areas and limiting exposure under these is recommended.

Good travel habits remain important, even during 'green light conditions'. This includes exposing only one person at a time on a slope, watching your partners closely and having an escape route planned in case the snow moves. 

Summit Lake, South of Johnson Pass and North (in parts of the Girdwood Valley):  A reminder that the snowpack remains thinner in these areas with a poor structure. There is still a chance for triggering an avalanche deeper in the snowpack in these areas. Read the Saturday Summit Summary HERE and an observation from Fresno Ridge HERE.


Primary Concern

Happy St. Patrick's Day! A small pot of gold was found yesterday in the Spencer Glacier area where a few inches of snow fell early yesterday morning. For the rest of our region surface conditions are made up primarily of thin crusts, hard wind board on ridges and near surface facets (recycled powder) in areas sheltered from the recent winds. Although the avalanche danger is LOW, there are a handful of avalanche problems that could catch you off guard in dangerous terrain. Be aware of the following:

Wind Slabs:  In places that received a few inches of snow yesterday watch for blowing snow and shooting cracks where newly formed shallow wind slabs could be tender today. Older, stiffer wind slabs such as the one triggered on Seattle ridge last weekend will be less likely to trigger by a skier or snowmachiner. Smooth pillowed snow on steep unsupported features or in rocky areas will be the most suspect places to initiate an old wind slab.  

Loose Snow Avalanches (Sluffs): Dry sluffs on steep slopes are probable and have been fast moving this week.  Keep terrain choices and potential consequences in mind when managing sluff.

Glide Avalanches: Glide cracks continue to slowly open above popular terrain on Seattle Ridge and in other zones across the advisory area. These may release at any time.  Minimize exposure time spent under visible cracks.

Cornices: Cornices should always be given an extra wide berth if travelling along a corniced ridge.  Like glide cracks, minimize your exposure time spent under these backcountry bombs. 

Persistent Slabs and Deep Slabs: There are various weak layers in our thin snowpack. Buried surface hoar sits 1-3+' below the surface and faceted snow sits in the mid and base of the pack. Given plenty of time and a lack of changing weather, these weak layers (with varying degrees of strength) are in a ‘dormant stage’.  Although unlikely, an avalanche breaking deeper in the pack isn't completely out of the question in areas such as Johnson Pass, Lynx Creek and in parts of Girdwood Valley (especially around Crow Pass).  A cornice fall or glide crack release could also be a large enough trigger to wake up one of these persistent slabs.  

Skier triggered sluff on the South Face of Sunburst.

 

"This is a video re-cap of the last month or so of weather in Alaska as seen from the GOES satellite imaging system. If you watch carefully you might actually be able to see our snowpack blowing into the Gulf..." Thanks Tobey Carmen for the timelapse.


Mountain Weather

Yesterday morning skies were cloudy becoming clear and sunny by early afternoon. A few inches of snow fell near Spencer Glacier with only a few flakes spotted in the rest of our forecast zone. Daily warming increased from the single digits F into the low 20F’s mid day. Ridge top winds were light (5-10mph) from the North. Overnight temps near sea level dropped back into the single digits F. 

Another clear and sunny day is in our future. Day time warming may reach the mid 20F’s this afternoon. Night time temperatures should drop back into the single digits F. Ridge top winds, 5-15mph from the Northwest are expected to reach their peak by mid-day. No precipitation is expected. 

Cold and clear weather is expected throughout the weekend as high pressure continues to persist over mainland, Alaska. A series of fronts moving through the Gulf may bring light snow showers to coastal areas by Sunday, but no measurable amount of precipitation is expected. This pattern is expected through mid week.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  0 59 
Summit Lake (1400') 29 
Alyeska Mid (1700') 11  56 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 13  10 
Seattle Ridge(2400') 16 

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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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