CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Thursday, March 19th 2015
Created: Mar 19th 6:02 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
SLR Consulting
Special Announcement

Our most sincere condolences go out to the family and friends of Russell Miller who tragically succumbed to injuries suffered from an avalanche in the Cantwell area last Saturday.  CNFAIC staff are compiling information and will post an accident report in the near future.


The Bottom Line

There continues to be a CONSIDERABLE avalanche danger at and above treeline today.  Slab avalanches 2’ thick or more are likely and will require cautious route finding and conservative decision-making.  Avoid steep, wind-loaded slopes in the alpine and abrupt rollovers at and below treeline today.

The pre Saint Paddy’s day storm was the biggest of the season thus far and came in both upside down and resting on a facet/ crust combo (see photo below) in many areas.  Careful terrain management will be essential today as the old surface continues to adjust to this most recent load.


Primary Concern

A layer of feeble, faceted snow that made up last week’s surface continued to show signs of activity yesterday both in our snowpits and on our tour up Tin Can.  With 20- 24” of storm snow deposited upon this layer on Monday, natural avalanches are becoming less common but the poor structure of our snowpack is still proving ripe for human-triggered avalanches in the 2’ range, particularly near treeline.  Above about 3,000’ slabs may be thicker than 2’ as moderate to strong winds blowing from the NE loaded many leeward slopes yesterday.

The snow below tree line is quite heavy and still very active.  Extra caution is warranted as you travel through areas such as Tin Can trees or Eddies where you may encounter short, steep rollovers ending in terrain traps.  Small slopes are holding enough snow right now to bury a person.  Watch your slope angles (keep it sub 35*) and run out zones.  This will be extra important as you encounter other groups in the backcountry today vying for similar terrain.


Secondary Concern

Winds were moderate to strong from the northeast yesterday with visible plumes of snow erupting off of ridges.  In addition to loading south and west aspects the wind all but erased any signs of tracks or crown faces from Tuesday.  Given the structure discussed above, Monday’s storm combined with stiff winds yesterday are likely to have formed slabs 2’ or greater in the alpine today.  A stiff, drum-like surface, shooting cracks or whumphing will be indicators that you are dealing with a potentially unstable wind slab in the alpine.  Again, effectively managing your terrain and avoiding steep slopes will be key today.


Mountain Weather

Steady rain around Girdwood and the Turnagain arm gave way to partial clearing on Turnagain pass mid-day yesterday.  The rain snow line was observed to be around 1500’ with temperatures in the mid to high 30’s at Turnagain pass (1,000’).  Winds were moderate to strong at times, gusting into the 50’s and 60’s from the northeast (see photo below).  Snow accumulation around the Pass was minimal (~2”) with new snow struggling to keep up with the impressive settlement rates of Monday’s storm

Today we can expect temperatures again to be in the mid to high 30’s at 1,000’ and winds from the northeast, backing off slightly ahead of an approaching short-lived high pressure system that will begin to set up tonight.  A few showers this morning may add an inch or two of snow but the general theme for the day will be one of clearing.

We’ll start the weekend with clear skies tomorrow and then clouds building back in by Saturday as a weak north Pacific low moves into the eastern Gulf of Alaska.

Sticky surface snow and strong winds lead to wind-initiated roller balls at treeline on Tin Can.  photo: John Sykes

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  36 .2   55
Summit Lake (1400') 37   0  13
Alyeska Mid (1700') 35 0 .24 36 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 27   NE 24   67
Seattle Ridge(2400')  29  n/a 17   73

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