CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Friday, February 3rd 2017
Created: Feb 3rd 5:09 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.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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
The John Byrne Family
Special Announcement

The Southern Kenai Mountains including Seward, Snug Harbor and Lost Lake continue to have an unstable snowpack.
Human triggered large avalanches, breaking near the ground, are possible.
Please see link above for recent activity. Another 1-2' of wet heavy snow fell Tuesday and Wednesday, adding more load to a snowpack with weak snow near the base. Keep in mind avalanches can be triggered remotely, from below or mid-slopeCareful snowpack evaluation and cautious route-finding is essential. 

Placer and Twenty Mile: Travel is extremely difficult right now due to recent rain, warm temperatures and overflow. This area will remain open in anticipation of forecasted cooler temps but travel is NOT currently recommended for novice riders.

Hatcher Pass avalanche conditions: If you are considering heading this way - please check the recent observations for Hatcher Pass and their Saturday morning advisory tomorrow!!


The Bottom Line

A generally LOW avalanche danger exists in the mountains surrounding Turnagain Pass. Point release avalanches triggered by the sun and/or humans on steep slopes with a Southerly tilt will be possible again today. Cornice falls are also possible, and occurred yesterday, with the warm sunny weather. Watch for winds that may pick up today to form soft and shallow wind slabs on leeward slopes. Lastly, triggering a large avalanche breaking 2-4' deep in weak snow deeper in the pack is unlikely but not out of the question. 

Girdwood Valley:  A MODERATE avalanche danger exists in this area due to a thinner snowpack with weak snow found near the base. The possibility exists for large avalanches, breaking near the ground, to be triggered in thin areas and/or remotely from ridgelines or the bottom of slopes.

Placer Valley, Johnson Pass and areas South of Turnagain Pass:  There is a MODERATE avalanche danger in these areas as well for large slabs breaking near the ground. We have little information in these zones, but we do know there is weak snow near the base of the pack, similar to the Southern Kenai and Girdwood Valley.

Summit Lake: An unstable snowpack exists in the Summit Lake area and similar to the regions above, human triggered avalanches breaking near the ground are possible. Make sure and check the Saturday Summit Summary HERE.

** It will be critical to carry rescue gear and maintain safe travel protocol this weekend - such as exposing one person at a time, grouping up in safe zones, having escape routes planned and watching your partners!


Primary Concern

It's that time of year! The sun is out and affecting the snow in terrain on the Southern half of the compass.  With 4-8" of loose snow on the surface over a dense base, watch your sluffs and watch how the sun is affecting the snow around you.  

Wind Slabs? There is a slight chance winds could bump up enough to form soft shallow slabs on leeward slopes. Although the main flow will be Northwesterly, loading Southeasterly aspects, this pattern also creates a Southerly flow along the East side of Turnagain Pass which loads North aspects (such as Sunburst and Tincan). 


Secondary Concern

With February already here along with a high pressure stint bringing sunshine, it may be easy to forget many areas in Southcentral have a poor snowpack structure. As mentioned in the bottom line above, weak snow near the base of the pack exists on slopes with a thinner snow cover. The heart of Turnagain Pass has drawn the lucky ticket and the pack is deeper and stronger with avalanche concerns focused on surface instabilities (sluffs and shallow fresh wind slabs). 

If deciding to venture to the periphery zones, watch for recent avalanche activity, listen for whumphing (collapsing of the snowpack) and cracks that shoot out from your snowmaching, skis or snowboard. There also can be no warning signs before an avalanche is triggered. This type of avalanche is often triggered in a thin spot, near rocks or on the edge of the slab. These can also be triggered by large groups and/or snowmachines on, near or under slopes. Again it will be critical to maintain safe travel protocol, again as mentioned above.

 

 


Additional Concern

Cornice falls are possible with warm temperatures and sunshine. These could release naturally and be near the tipping point that person breaks them off easily. Keep a wide berth when on ridgelines and limit time underneath. 

 Photo: Cornice fall yesterday in Warmup Bowl in the Seattle Creek drainage. Triggered from a person on the ridge later in the day.


Mountain Weather

It was a brilliant sunny day in the mountains yesterday with little to no wind at all elevations! Temperatures were cool (~10-15F) in valley bottoms and warmer (20-30F) on the ridgelines. 

Today will be much of the same with two slight changes, but first, bring your dark lenses as the sun will be intense. 1) Ridgetop winds have just bumped up slightly this morning and could be breezy for the day (5-15mph from the North and West, gusting 10-20mph). Temperatures have climbed overnight at the high elevations and sit around 32F - valley bottoms have decreased and sit in the single digits... Another blocking high-pressure and associated stout inversion is settling in...

These conditions are expected to persist all the way through the weekend and into Monday. There's no hint of a storm cycle in the foreseeable future, but we could get some flurries the middle part of next week.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 19   0 55 
Summit Lake (1400') 10   0 24 
Alyeska Mid (1700') 21  49 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 29  16 
Seattle Ridge(2400') 24  NE  10 

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