CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Monday, January 2nd 2017
Created: Jan 2nd 5:44 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.
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
  • As of yesterday Alaska DOT has not cleared the Turnagain Pass motorized lot. Please park safely and be respectful of any plow efforts to clear this lot. 

  • If heading to Hatcher this New Year - unstable conditions exist - check the Hatcher Pass advisory HERE Mark your calendars for the FREE rescue workshop at Hatcher Pass on January 14th. More info HERE.
  • For Turnagain Pass December Weather History Chart click HERE.

 


The Bottom Line

A MODERATE avalanche danger remains in the alpine where triggering an isolated wind slab or a deeper slab 2+’ thick is possible on steep wind loaded slopes that haven’t avalanched. Within the trees and at lower elevations there is LOW avalanche danger, where triggering an avalanche is less likely. 

In the periphery zones of Johnson Pass and Summit Lake a much shallower snowpack exists and it may be easier to trigger a slab avalanche in these areas. Check out the Summit Lake Summary HERE and an observation HERE from Tenderfoot from yesterday.


Primary Concern

PERSISTENT SLAB AVALANCHES (In our current case: Hard WIND SLABS SITTING ON WEAK SNOW): A big wind event that occurred on December 30th has stripped many Southern and Western ridgetops and left an unusual loading pattern for our region; loading Northern and Eastern aspects. This wind event as well as the Christmas snow storm (a week ago) caused widespread avalanching in the area. Several persistent weak layers are buried within the snowpack (facets and buried surface hoar), but strong supportable snow may make it tough to find the right trigger spot.  

Some uncertainty remains today with how the warm inverted air temps (approaching 40F) will affect the snowpack in the alpine. Although radiation from the sun at this time of year is minimal, whenever temperatures remain above freezing for 24 hours it is worth keeping in the back of your mind. Be skeptical of supportable and hollow sounding snow on steep slopes. Likely trigger spots will be in thinner areas of the snowpack in steep rocky terrain or on unsupported slopes that haven't avalanched. Triggering a small isolated wind slab or a deeper slab 2+ feet is becoming more difficult, but is possible for a person or snowmachine to tip the balance. Obvious signs like cracking and ‘wumpfing’ are becoming less common and may not be an early warning sign. 

Before exposing yourself to steeper terrain, ask yourself what will happen if the slope slides? Always practice safe travel habits to minimize exposure in avalanche terrain! 

  • Expose one person at a time
  • Watch your partner from a safe zone
  • Have an escape route planned
  • Watch for other groups

A closer view of the natural avalanches that occured on Corn Biscuit's North facing chutes last Friday (12/30.) Places that haven't avalanched with similar characteristics (rocky starting zones, top loading and cross loading) remain suspect. 

 

Most of the snow along Southern aspects have blown away making it unlikely to trigger an avalanche in these areas.  

 


Mountain Weather

Yesterday skies were sunny and clear with light Northwest winds. A large temperature inversion was observed, 12F at 1000’ and 33F at ridge tops, which caused valley fog in Turnagain Arm. 

Overnight ridge top temps  increased into the high 30F’s Turnagain Pass and low 40F’s in the Girdwood Valley. Valley temps have remained around 10F. Winds have remained light and no precipitation was recorded. 

Today expect a similar inverted weather pattern with above freezing temperatures in the alpine and temperatures near 10F in valley bottoms. This will trap dense Valley fog in and along Turnagain Arm.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33  38 
Summit Lake (1400') 13  12 
Alyeska Mid (1700') 31  25 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 35  13 
Seattle Ridge(2400') 36  NW  16 

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

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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC