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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Saturday, March 18th 2017
Created: Mar 18th 6:07 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
Alyeska Pipeline Service Company
The Bottom Line

The avalanche danger remains LOW 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. Limit your exposure under cornices and glide cracks.

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, Johnson Pass, Lynx Creek and the Northern portion of Girdwood Valley: There is still a chance for triggering a deeper more dangerous avalanche in these areas. Read the Saturday Summit Summary HERE.


Primary Concern

With the exception of a few inches of snow that fell in the Placer/Skookum zone on Thursday morning, it has been 24 days without precipitation in 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 has been at LOW for almost two weeks, there are a handful of avalanche problems that could catch you off guard in dangerous terrain. Be aware of the following: 

Wind Slabs:  Old stiff wind slabs, such as the one triggered on Seattle ridge last weekend, will be stubborn to trigger. Smooth pillowed snow on steep unsupported features or in rocky areas will be the most suspect places to initiate an old wind slab. Small fresh wind slabs are also possible near ridgetops surrounding the Skookum/Placer Valley due to recent snow (2-3") and moderate winds that kicked up yesterday afternoon. 

Loose Snow Avalanches (Sluffs): Loose unconsolidated snow can still be found, and could be fast moving in steep terrain. In Skookum/Placer new snow may be easy to initiate and wet-loose point releases are possible on Southerly aspects due to solar heating. These will likely be small, but 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 traveling 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 on the Northern side of Girdwood Valley (near Crow Pass). 

Surface conditions around our region are highly variable 

 


Mountain Weather

Yesterday was another clear and sunny day. Daily warming caused temperatures in the single digits F to increase into the low 20F’s by mid day.  Ridge top winds, 5-15mph, varied in direction from Southwest to Northeast. Overnight temperatures dropped back into the single digits F.

Another clear and sunny day is in our future. Temperatures are expected to rise from the single digits into the low 20’s - a similar pattern as yesterday. Ridgetop winds are expected to be light and variable. No precipitation is expected. By evening light cloud cover is anticipated and temperatures should remain in the teens F overnight. 

Tomorrow scattered snow showers are possible, but not much accumulation is expected. High pressure over mainland, Alaska continues block a series of fronts in Gulf of Alaska, just South of us. Luckily there is a pattern shift is in the forecast late this week as the  “polar jet weakens over the northwest mainland.” At this point there is not a lot on the horizon for snow, but this is a good first sign. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 59 
Summit Lake (1400')  0 28 
Alyeska Mid (1700') 10  56 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') WSW  15 
Seattle Ridge(2400') NE  19 

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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