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Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, January 21st 2019 7:00 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

A generally LOW avalanche danger exists across all elevations bands for the Turnagain area. Triggering a slab avalanche is unlikely but not impossible. Identify glide cracks and avoid/limit your exposure time under this unpredictable hazard. Give cornices a wide berth and watch your sluff.

GIRDWOOD / PORTAGE / PLACER:  North of Turnagain Pass received more snow in the last storm. The chance of triggering a slab avalanche increases if traveling in the Alpine in this zone. 

SUMMIT LAKE / JOHNSON PASS:  A poor snowpack structure exists in this area, which is very different than Turnagain Pass. Triggering a slab avalanche is trending toward unlikely, yet may not be out of the question. Evaluate the snowpack and terrain. 

 


 Show the Complete North American Avalanche Danger Scale
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.
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Avalanche Problem 1

After a sunny weekend of generally stable conditions the weather change today is not expected to affect the avalanche danger, as not much snow or wind is forecast. However, it will be important to pay attention if conditions change. The snow surfaces are not ideal for new snow bonding to the old snow. This will become a real concern when we do get snow accumulation.

Finding an isolated slab especially in upper elevation terrain in Girdwood, Portage or Placer is not completely out of the question. This part of the advisory area received more snow in the last storm. There has been one known human triggered avalanche that failed in the facets below the new snow, which was last Thursday in the Placer Valley. With colder temperatures and no additional loading observations and snowpack tests have been pointing towards a stable snowpack. 

Low danger does not mean no danger. Practice good travel habits, such as exposing one person at a time, watching your partners and grouping up in safe zones are key ways to minimize risk. Ease into steep terrain and factor in the consequences should you encounter one of the following:

  • An outlier slab avalanche: 
    • Triggering a slab avalanche would most likely occur on an exposed 'unsupported slope' that sits above a cliff or steep rocky terrain. An old wind slab or a pocket of buried near surface facets and/or surface hoar 5"-2' below the surface may be lurking in an isolated area.
  • Glide avalanche:  
    • Identify glide cracks and avoid spending any time under these features. Glide avalanches are completely unpredictable and not human triggered.
  • Cornice fall: 
    • Remember cornices often break farther back from ridges than expected. Give them a wide berth.
  • Loose Snow avalanche (sluff):
    • Be aware of fast moving surface snow in steep terrain. 


The next buried weak layer??? Surface hoar on a melt-freeze crust, 1-19-19. Photo: Troy Tempel


Additional Concern

Persistent Slabs

South of Turnagain - Johnson Pass/Summit Lake zone: A poor snowpack structure exists in these areas.  Multiple mid-pack weak layers of facets and buried surface hoar have been found as well as a facet/crust combination in the bottom of the snowpack. No recent avalanche activity and calm weather has allowed the pack to slowly adjust. However, it still important to evaluate the terrain and snowpack. Upper elevation terrain with hard, wind-affected snow over the buried weak layers is the most suspect. 


Mountain Weather

Yesterday: Sunshine and clear skies with some valley fog. Temperatures ranged from single digits to high teens. Winds were easterly 5-15 mph. Overnight clouds moved in and temperatures increased to the high teens and 20Fs. Winds bumped up slightly gusting into the 20s. 

Today: Mostly cloudy skies and a chance of snow showers. Winds will be easterly 5-15 mph with gusts into the 20s. Temperatures will be in the 20Fs.  A chance of snow is forecast overnight with steady temperatures and similar winds. 

Tomorrow: Tomorrow's weather looks to be very similar to today and then the chance of precipitation bumps up overnight into Wednesday. There is warm air associated with the southerly flow pushing into the area and may bring some liquid precipitation to the lower elevations. The overall storm track is still uncertain. Stay tuned and think cold thoughts! 

*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 18  50 
Summit Lake (1400')   0    21 
Alyeska Mid (1700')  18    0   38 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 15  NE  24 
Seattle Ridge(2400')  19   *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: Mar 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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
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