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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Sunday, December 6th 2015
Created: Dec 6th 5:09 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
The Bottom Line

A generally LOW avalanche danger exists across all elevations bands for the Turnagain Pass zone. In steep terrain near rocks where the snowpack is thinner triggering a slab 1-3’ thick is unlikely, but could have high consequences. Ease onto steep slopes one at a time and be mindful of people below you and on adjacent slopes.

*If venturing into the 'periphery' forecast zones, such as Girdwood Valley, Silvertip and Summit Lake areas, more caution is advised due to limited information about the snowpack in these areas.


Primary Concern

Yesterday Turnagain Pass saw many 'slope testers' (skiers and riders) pushing into steeper terrain and no red flags (recent avalanches, whumphing or shooting cracks) have been reported in nearly a week. Since the Thanksgiving rain event ended over a week ago a wet snowpack has frozen leaving a stable stout crust below 2500’. In the Alpine snow depths vary from 1-5’ thick with a generally thinner snowpack on Northern and Eastern slopes. In areas where the snowpack is thinner a slab 1-3’ thick sits on top of pockets of weaker snow near the ground. Because we lack x-ray vision it is unclear how widespread this basal faceted snow is across any given slope. This poor structure has shown some propagation potential in test pits this week, making it difficult to ignore. Triggering such a problem is an outlier, yet is possible in thinner areas near rocks. Caution is warranted if planning to push into steep complex terrain above 3000'. 

Snow depths in the higher elvations of Pastoral averaged between 3-5' thick, but a poor structure can still be found. Click Here to view yesterday's observation.


Additional Concern

Calm winds this week have left 8” of low-density surface snow to settle out making skiing and riding conditions quite good. Small natural point release 'sluffs' were observed yesterday on steep slopes in the Alpine. This is a minor concern, not enough volume to bury a person, but has the potential to knock you off your feet. 

The snow quality right now is arguably the best it’s been in over a year so no doubt the usual zones in Turnagain will be crowded.  Keep other adjacent groups in mind as you are moving through the mountains today and maintain good backcountry etiquette.  Wear and know how to use your rescue gear, expose one person at a time on a slope, discuss potential consequences if a slope does slide and don’t ski on top of other parties.

Northern aspect of Magnum ridge, where small natural point releases were observed yesterday.

 


Mountain Weather

Yesterday above 1000’ skies were clear, temperatures were around 20F and winds were calm. In the surrounding valleys a dense fog left behind a trace of new snow.

Today a similar pattern is expected. Temperatures should remain in the low 20F and gradually warmer in the Alpine as a result of a slight inversion. Ridgetop winds are expected to be light from the Northeast, with mostly clear skies.

The first hint of a shift in the weather is Tuesday for possible snow.



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 20F  trace  0.05  24 
Summit Lake (1400') 15F   0 11 
Alyeska Mid (1700') 20F  trace   0.05 20

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 20F  NE 
Seattle Ridge(2400') 19F  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: 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

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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
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