CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Sunday, March 5th 2017
Created: Mar 5th 6:22 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
Alaska Airlines
Special Announcement

Strong winds over the past several days have affected the snow/avalanche conditions in many areas of Southcentral Alaska and the Kenai. See this report sent in to us from the Lost Lake zone on the Southern Kenai. Additionally, a natural avalanche was viewed in motion in the South Fork of Eagle River on Friday. For avalanche conditions at Hatcher Pass, see the HPAC Saturday morning advisory!

Avalanche Rescue Talk:  Stop by Ski AK in Anchorage for a discussion on backcountry rescue Tuesday evening! The focus will be on organized rescue, presented by Bill Romberg (AMRG) a rescue specialist with 150 Search and Rescue missions here in Alaska. The evening will begin with a short 'state of the snowpack' report by the CNFAIC. See you Tuesday night - more details HERE!!


The Bottom Line

A MODERATE avalanche danger remains in the Alpine of Johnson Pass/Lynx Creek and parts of the Girdwood Valley, where wind loaded slopes have the potential to step down and trigger a deeper avalanche. It is these periphery areas that are keeping the danger elevated in our forecast zone. 

In Turnagain Pass, there is a generally LOW avalanche danger where triggering a small isolated wind slab is becoming stubborn and difficult to trigger. This avalanche problem is not likely to bury a person. Remember LOW danger does not mean NO danger, steep terrain could have high consiquences should a small wind slab or cornice fail above a terrain trap. Using safe travel protocol and evaluating the terrain for consequences will be important. 

*In Summit Lake, a widespread natural avalanche cycle occurred this week and heighten avalanche danger remains in this zone. Please see the Saturday Summit Summary HERE


Primary Concern

Ridgetop winds should again be moderate to strong - in the 15-25mph range from the Northwest. This is the same forecast we have seen over the last 3 days and Turnagain pass has either remained protected or the snow has blown away.  There are areas that have been partially spared by the brunt of the Northwest winds this week along the East(non-motorized) side of the road of Turnagain Pass. Folks have been able to find soft snow and venture further into the mountains without incident. That said, there are areas that have not escaped the major winds. A report yesterday confirmed Seattle Ridge to be scoured and hard pack, and most of the loose snow has blown away. Triggering a small hard wind slab is not out of the question in steep terrain in either area. Although these wind slabs will be tough to trigger, high consequence terrain (steep rocky area and and under a loaded convexity) will be the places that a wind slab could take you for a ride. Intenitfy these features and be aware of the consequences of the terrain you are riding in. 

***Although its unlikely today should you see blowing snow along ridge tops or experience a shooting crack these will be signs that wind slabs could be tender.

Smooth or pillowed surfaces, especally under a convexity or in steep rocky terrain are places to find a wind slab.

A good example of a corniced ridge that if triggered could take you for an undireable ride. Give corniced ridges lots of space! Goldpan - South face.


Additional Concern

In Turnagain Pass where the snowpack has become old and tired, good stability has been found within the deeper layers of the snowpack including as far South as Lipps. Slope testers have been stepping into steeper terrain this week without incident both in Turnagain Pass and in many areas of the Girdwood Valley. There have been no reports of avalanche activity within the older layers of the snowpack in Turnagain Pass for several weeks.   

However, the wind event that started last Monday night (2/27) did cause a natural avalanche cycle in Lynx Creek/Johnson Pass zone with slabs ranging in size from 1-2’ deep with wide propagation, likely failing on the February 9th buried surface hoar. The other area in question is the Crow Pass zone, where little is known about how this shallow snowpack has faired after a week of strong winds. Until proven innocent these periphery zones remain suspect for triggering a deeper more dangerous avalanche. The layers of concern in these areas are the buried surface hoar 1-3' deep and facets in the mid and base of the snowpack


Mountain Weather

Yesterday was another day of clear sunny skies and cold temperatures at all elevations. Daytime warming allowed the mid and lower elevations to warm into the low 20Fs. Ridgetop winds during the past 24-hours have averaged near 10mph with gusts into the 30's from the Northwest. 

As Southcentral Alaska sits in a holding pattern of sorts, we can expect similar sunny skies today with continued Northwest winds. Temperatures should warm again today and may reach the low 20F's below 3,000'. Ridgetop winds are expected to remain from the North and West in the 15-25mph range with stronger gusts.  

Clear skies and cold temperatures are expected over the next week as a blocking pattern of high pressure over Alaska dominates mainland, Alaska. Keep tabs on what the NWS is finding at the bottom of their Forecast Discussion - Long Term Forecast!

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 10  62 
Summit Lake (1400') 10  29 
Alyeska Mid (1700') 13  58 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 23 
Seattle Ridge(2400') 10  NW  12  35 

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