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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Friday, January 6th 2017
Created: Jan 6th 5:06 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
Alyeska Pipeline Service Company
Special Announcement

UPCOMING EVENTS:

  • Join CNFAIC and AMDS at the Turnagain Pass motorized lot this Saturday at 10:30am for a "passing off" of the keys celebration (keys to a brand new 2017 Ski Doo Summit SP 850)! HUGE thanks to AMDS and BRP/Ski Doo for granting the Friends of the CNFAIC a new loaner snowmachine for the season!! Stick around for a quick state of the snowpack discussion after!
  • Discussion on Backcountry RESCUE presented by team members of the U.S. Air Force 212th Rescue Squadron (RQS/PJ's) and Alaska Mountain Rescue Group (AMRG). Details HERE!
  • There is a Kenai Peninsula Avalanche Information Workshop this Sunday, January 8th at 5:30 pm at the Flats Bistro. Hope to see you there! More info HERE.


*Its that time of year again, PFD time! If you are feeling generous and want to support your local avalanche center, Pick Click Give, makes it really easy to become a supporting member of CNFAIC.


The Bottom Line

A MODERATE avalanche danger exists on steep terrain above the trees where winds have loaded slopes. Although the very strong winds have blown much of the snow away, expect to find shallow wind slabs that formed off ridgelines and lower on slopes. Watch for any steep slope that harbors recent wind deposited snow. Additionally, these wind slabs may overload buried weak layers and triggering a larger and more dangerous hard slab avalanche exists. 

Lower elevations that have escaped the winds, along with upper elevation slopes that are wind scoured, have a LOW avalanche danger where triggering an avalanche in unlikely.


Primary Concern

Very strong "outflow" winds impacted the region yesterday. Cold arctic air rushing down from the North battered the mountains. What soft snow did remain after the Dec 30th wind event was likely taken away with this Jan 5th wind event - a bit like salt on the wound! We only know of one small natural wind slab that released on an Easterly aspect in the Summit Lake area yesterday. Otherwise, there was just too little snow available for transport to produce natural wind slab avalanches. 

For Today:  Watch for new wind slabs from yesterday, overnight and today (winds are forecast to be moderate from the North and West). These slabs are likely to be shallow, very stiff and could surprise you on a steep slope. Watch for these in any location with wind loading, including lower on slopes. These also have the potential to overload buried weak layers and produce a much larger and dangerous avalanche. The Easterly face of Seattle Ridge is an example of where winds have been loading and known buried weak layers exist.

Safe travel protocol is your friend and if you head out today, remember to expose one person at a time, watch your partners, have an escape route planned and group up in safe zones.

 

Significant wind transport along Wolverine Ridge (seen from Portage). Winds along this ridge were more Southwesterly due to "terrain forced flow" in complex topography. 

 

The Summit Lake and Kenai Mountains got hit as well with these impressive winds. Below are plumes coming off the Southwest shoulder of Silvertip Peak (far left). 

 


Secondary Concern

Although the snowpack is wind hardened and tired, it does have a poor structure. There are a variety of weak layers in the middle of the pack as well as at the bottom. The slab on these weak layers is quite variable and hard - and though difficult to trigger, the possibility does exist. Steep wind loaded slopes (Northern and Eastern) that haven’t avalanched yet are the most suspect. Likely trigger spots are in thinner areas near rocks. Obvious signs like cracking and ‘wumpfing’ are becoming less common, making it more difficult to assess slope stability. Heavier loads, such as snowmachines or large groups of people can also be a trigger. 

In the periphery areas (Girdwood, Johnson/Lynx Creek and Summit Lake) where a thinner snowpack exists, several observers have experienced collapsing/wumpfing in recent days. 


Additional Concern

Believe it or not, 3 glide avalanches have occurred in the past 5 days in the Turnagain Pass zone. These are SE aspect of Lynx CreekSE aspect of Seattle Creek, and the SW face of Eddies. Along with recognizing wind affected snow, keep an eye out for glide cracks and limit time under these. They can have a knack for releasing during cold weather.


Mountain Weather

Extremely strong Northerly winds impacted the Southcentral mountains yesterday. Skies were mostly clear, but winds were averaging as high as 54mph with gusts to 79mph. These winds brought temperatures down to ~10F on the peaks but scoured out the cold air in the valleys where temperatures rose to the upper 20'sF.

Overnight we have seen decreasing winds, but we are still expecting the North flow to be moderate - averages 10-15mph with gusts into the 30-40's. Temperatures should remain chilly, 10-15F at most elevations and valley bottoms. Skies look to be mostly clear today.

It seems as though the blocking area of high-pressure over mainland Alaska will persist into next week. Along with this will be clear skies, cold temperatures and no expected precipitation.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 19  35 
Summit Lake (1400') 21  11 
Alyeska Mid (1700') 20  23 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  12 NW  11  63 
Seattle Ridge(2400')   16  38  79 

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.
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