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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Wednesday, December 7th 2016
Created: Dec 7th 4:45 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
Key Bank
Special Announcement

Planning on taking an avalanche class? The Friends of the CNFAIC is offering two avalanche scholarships through the Rob Hammel fund. Both scholarships are for $500. One is for avalanche professionals and the other is open to anyone!  The deadline for both scholarships is Dec 15th! For more information click this link HERE

Mark your calender for next week's Fireside Chat: Avalanche Awareness and Rescue w/CNFAIC in Girdwood at the Glacier Ranger Station, 145 Forest Station Road
December 15 @ 6:30 pm - 8:00 pm FREE
Join CNFAIC forecasters for an evening of avalanche awareness with a focus on recognizing obvious clues to instability and companion rescue. 


The Bottom Line

The avalanche danger is MODERATE on all slopes near and above treeline. Triggering a slab avalanche 1-2+' thick is still possible and the likelihood goes up as one travels to areas that have had less traffic this season. This is due to a buried layer of surface hoar that remains reactive. Additionally, triggering a wind slab avalanche is also possible today on steep slopes that have been loaded by winds over the past week.

Below 2000' in the trees where the snow is loose and unconsolidated the avalanche danger remains LOW.

If headed to Summit Lake check out the Summit Lake Summary HERE and a recent observation from Fresno Ridge on Sunday, Dec.4, HERE.

***Out of area: Click HERE to check out an observation about a human triggered avalanche in the Anchorage Front Range on Dec. 5.


Primary Concern

The buried surface hoar remains a nagging concern in the snowpack. Don’t forget this layer is on all aspects and continues to show propagation potential in test pits above 2000’. The other important thing to note is the slab character is becoming denser with recent wind events, which means the slab could break above you once well onto the slope.  During the past two weeks, many popular slopes have avalanched (removing the weak layer), and been covered again by recent snow. This makes it really hard to know the full extent of which slopes still have this weak layer set-up, especially in places that haven’t seen much traffic. Most of this activity has been on the popular Southwest slopes of Sunburst and Tincan and little is known about places less traveled. Yesterday digging on a section of terrain that hasn't slid on Sunburst but has seen some skier traffic showed the surface hoar was still easy to distinguish in the snowpack and still reactive. The presence of the surface hoar should be part of your slope choices today and be something you keep in mind when we get our next loading event.  Manage your terrain and use safe travel protocols. 

  • Expose one person at a time
  • Group up in safe zones
  • Have an escape route planned
  • Watch your partners and where other groups are around you

Buried surface hoar in a snow pit at 3200' on Sunburst, December 6th.

 


Secondary Concern

The winds yesterday calmed down by mid-day. Monday night into Tuesday morning they were strong enough to transport soft snow around, filling in tracks and depositing snow on the leeward side of terrain features. Today two types of wind slab are still possible and warrant caution if venturing into steep wind loaded terrain. Softer more tender pockets of wind slab may break from your skis/board while traveling. These may still be large enough to knock you off your feet or surprise you in the wrong place. In addition stiff old wind slabs from last weeks wind event may pop once you are farther out onto the slab and can be tricky because of the supportable character. Be wary of hard over soft snow, hollow sounds and steep slopes with obvious deposition in the start zone. These wind slabs have the potential to be deeper and harder to manage. 

 Cracking along ridgeline on Sunburst yesterday

Sunburst with wind effect and old tracks 

 


Mountain Weather

Yesterday was partly to mostly cloudy with no precipitation. Temperatures were in the high teens to low 20s. Winds were mostly light but there were some gusts into the high 20s early in the day. Last night temperatures stayed in the 20s and winds were light.

Today will be mostly cloudy with a chance of snow showers throughout the day and temperatures in the 20Fs. Winds will be light and easterly. Tonight will be similar with slightly cooler temperatures. 

Tomorrow the chance for snow showers and clouds decreases in the afternoon and the sun might shine for a bit. There is a chance of snow showers again on Friday and then clear skies and colder temperatures return for the weekend. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  22  0 20 
Summit Lake (1400')  19 0  0   4
Alyeska Mid (1700')  22  0  0  10

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  18  NE 27 
Seattle Ridge(2400')  20  ESE  5 18

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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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