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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Monday, December 5th 2016
Created: Dec 5th 4:42 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
Special Announcement

There is a FREE Avalanche Rescue Gear discussion at the Alaska Avalanche School (1025 Orca St, Unit N, Anchorage) TONIGHT from 7-9 pm. Come join the conversation! 

Interested in forecasting snow/weather conditions for your day in the backcountry, or your weekend trip? Join CNFAIC forecaster Wendy Wagner Tuesday night for a FREE mountain weather talk at Ski AK in Anchorage - 6:30-8pm!!

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


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 recently been loaded by winds. 


Primary Concern

Clear skies are allowing folks to venture further into the backcountry and people are choosing to go into steeper terrain. Remember the buried surface hoar as you get into areas that haven't been ridden. These 'less traveled slopes' are the most likely places to trigger an avalanche. The layer of buried surface hoar (from Nov. 16) sits roughly 1-2+ feet below the surface and it is still a concern. Observers have been still been able find this buried persistent weak layer in snow pits throughout the region and it is still reactive in stability tests.  It's a complicated situation since slopes that have avalanched are generally stable, but those that have not remain unstable. Telling between the two may be difficult as subsequent snow and wind have covered up the evidence. Continue to be on the lookout for signs of instability, cracking and collapsing. A group on Seattle Ridge reported large whumpfs when they were traveling off the main skin track. Manage your terrain and use safe travel protocols. Always ask the question what if this slope slides? What are the consequences? Where will I end up? 

  • 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

Snow pit from November 3rd illustrates the buried surface hoar issue. Photo: Wendy Wagner


Secondary Concern

It is hard not to feel and/or see the effect that winds that blew after Wednesdays storm had on the snow once you get into any open terrain. Wind slab avalanches remain a concern on all exposed slopes where winds have formed drifts and slabs. There is a lot of wind effected snow out there and many of the slabs found over the weekend felt stubborn and hard to move. On Friday, one party found a touchy slab on a steep North facing shoulder of Cornbiscuit that released on a ski cut. This is a good example of not letting your guard down even if you see no signs of instability. A big thanks to the party that wrote in, you can read their account HERE. The wind slab may also overlay the buried surface hoar and triggering may release a deeper more dangerous slab if you find the wrong spot. Be wary of hard over soft snow, hollow sounds and steep slopes with obvious depostion in the start zone. 

National Avalanche Center example of Cross Loading

Photo from Eddies yesterday shows wind loading and a small pocket of wind slab. Photo: Andy Moderow

  


Mountain Weather

Yesterday skies were clear and it was cold. Temperatures hovered around 0F and light N winds added to the overall chill. Overnight temperatures in the valleys dropped into the negatives while ridgeline weather stations showed temperatures rising into the teens due to an inversion. Winds were light and variable.

Today will be mostly clear with clouds building in the evening as the next pulse of moisture moves over the area. Temperatures will be in the low teens and East winds will be light. Tonight will be mostly cloudy with a chance of snow showers. Temperatures will be in the single digits but rise overnight. Winds will continue to be light and easterly. 

Tomorrow will be mostly cloudy with a chance of snow showers, temperatures in the low 20Fs and light east winds. The NWS forecast describes the overall pattern for the remainder of the week as cold and dry due to a blocking pattern that will keeping the cold air mass over us. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') -1   0  0 22 
Summit Lake (1400') -3  0  0  4 
Alyeska Mid (1700')  1  0  0  11

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  -2 NNE  17 
Seattle Ridge(2400')  7 variable  13 

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: Mar 25, 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: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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