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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Monday, January 9th 2017
Created: Jan 9th 5:22 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

UPCOMING EVENTS!!:

  • Tuesday January 10th, Backcountry RESCUE discussion by team members of the U.S. Air Force 212th Rescue Squadron (RQS/PJ's) and Alaska Mountain Rescue Group (AMRG). Details HERE!
  • Thursday January 12th, 6:30pm, basic avalanche awareness and discussion by CNFAIC on the current snowpack in Turnagain Pass at the Alaska Avalanche School, Details HERE

* Hatcher Pass continues to have unstable conditions, check the Hatcher Pass advisory HERE if you are thinking of heading this way. Also - mark your calendars for the FREE rescue workshop at Hatcher Pass on January 14th. More info HERE


The Bottom Line

A generally LOW avalanche danger exists in the mountains surrounding Turnagain Pass. Although triggering an avalanche is unlikely, old hard wind slabs 1-3' thick remain. With the right amount of force it's not impossible for one to pop out. Most suspect areas are in steep rocky terrain where slabs are not supported from below. A variety of weak layers sit under these wind slabs and keeping up safe travel protocol is important despite the 'green light' conditions. Additionally, watch for glide cracks and avalanches, as these may be active this week.

In the periphery zones of Girdwood, Johnson Pass and Summit Lake a shallower snowpack exists and it may be easier to trigger a slab avalanche in these areas. Check out the Summit Lake Summary HERE.

 


Primary Concern

As sunny skies and calm weather remains over the area, the snowpack continues to adjust to the impacts of the high winds last week. It has now been 11 days since the last snowfall. Although we are still finding poor structure on slopes above the trees that have not avalanched, the slab continues to lose its reactivity in pits and there has not been a human triggered avalanche for a week. There are several weak layers sitting under the old hard wind slabs; these are facets and buried surface hoar in the mid-pack and facets at the base of the pack. Check out the video below for a look at a suspect trigger point (thin rocky area on an unsupported slope) from yesterday. 

The one change in weather today is the warming at the upper elevations. Check out the graph below of the Sunburst weather station at 3,812' that hit 39F this morning! Will this be enough warming to impact the surface conditions, or the slab? Likely not too much since the atmosphere is so dry and skies are clear (allowing the snowpack to radiate its warmth back into space).



Surface conditions? Riding and skiing has been reported to be nice, yet bottomless, in areas below treeline in soft 'recycled' powder. Above treeline, surface conditions are variable: wind affected hard/old slabs, anti tracks, sastrugi, breakable wind crust, and in some areas, interspersed with soft old faceted snow. 

As always, keep a lookout for whumphing and cracking in the snow. These are signs you found a slab that remains unstable and again a good reason to keep up safe travel protocol (expose one person at a time, group up in safe zones and have an escape route planned).

  

 

Pastoral Peak: Fairly well distributed grains of shale and dirt covering the Pastoral Glacier; an indication of how strong the winds were during the Dec 29 and Jan 5th wind events. (Photo: S. Galoob & J. Haffener)

 


Additional Concern

Glide avalanches are possible this week:  The warm temperatures at the upper elevations may enhance 'glide' in the snowpack. Watch for glide cracks to open up and a few may release. This pattern is similar to last week when 3 glide cracks released. Known cracks exist on the South face of Eddie's, Goldpan (behind the Magnum ridge), East face of Seattle Ridge (Northern end) and Southerly slopes near Johnson Pass.

Glide avalanche in Lynx creek from January 2nd


Mountain Weather

Sunny skies - calm winds and an impressive inversion is over the region! Yesterday we saw temperatures in valley bottoms between -5 and 5F where at the 3,500' ridgelines it was 35F (balmy). Winds were light and variable.

Today, upper elevation temperatures will be even warmer - overnight Sunburst weather station reports temperatures rising to 39F. Valley bottoms will remain cold, in the single digits, and ridgetops in the mid 30'sF. Winds are forecast to be 5-10mph from a Northerly direction and skies clear.

This pattern looks to persist through the week - but..... models are showing the blocking high pressure eroding by the end of the week and chance for precipitation this weekend. 




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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 19  34 
Summit Lake (1400') 11 
Alyeska Mid (1700') 21  22 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 35  NE  14 
Seattle Ridge(2400') 32 

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: Nov 18, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to 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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