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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, January 21st 2016
Created: Jan 21st 6:20 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
Medical Park Family Care
Special Announcement

She Jumps in collaboration with the Alaska Avalanche School & CNFAIC will be putting on a basic avalanche rescue clinic focused on companion rescue. Sorry guys, this is a women's specific clinic and will review efficient search techniques using a beacon, probe and strategic shoveling. This is a great opportunity to get some hands on practice with the help of an instructor. For more details click HERE.


The Bottom Line

Today a MODERATE avalanche danger exists in the Alpine and at Treeline. Triggering an isolated wind slab 6”-20” thick is possible on steep wind-loaded features. In places protected from the wind loose snow avalanches could be fast moving and easily knock you off your feet in the wrong place. Identify wind-loaded features, turn around if you see shooting cracks, and be conservative near high consequence terrain. Also avoid slopes with glide cracks and give cornices a wide berth today - both of these hazards are unpredictable.

A LOW avalanche danger exists below 1000’ where triggering an avalanche is unlikely.

If you are thinking of going to Summit Lake, be aware that different avalanche hazards exist within the snowpack. Click HERE to read the Summit Lake Summary from this last weekend. 


Primary Concern

Wind slabs: Over the last few days several wind events combined with over a foot of new snow have created fresh wind slabs up to 20” thick on leeward features. The good news is this new snow is bonding well with the old snow below, however not enough time has passed for this hazard to have completely healed. Wind slabs are likely to be tender and found on slopes steeper than 38°. Trigging an isolated wind slab in the wrong place, like over a cliff or above a terrain trap, could have high consequences.  Should today’s visibility allow for easy access into steeper terrain avoid wind-loaded features, watch for shooting cracks, and choose your terrain wisely.

Cornices: Already large cornices have received additional stress over the last 3 days.  Strong winds have been adding weight to their robust size and could be extra tender today. These backcountry bombs have a tendency to break farther back than expected and can send you for an undesirable ride.  Approach ridgelines with caution and avoid being on or directly below cornices features. 

Yesterday's poor visibility prevented a view into the alpine, but here's a photo from Tuesday, Jan.19th, of Tincan Proper. Note the large cornice near the ridge and wind-loaded pillow features. Above photo by Aleph J-Bloom

 

 

An observation yesterday from Seattle Ridge showed good bonding of new snow and old snow - however tender windslabs are suspect in steep terrain. Photo by Wendy Wagner 


Secondary Concern

In places protected by the wind 12” of loose unconsolidated snow could be fast moving in steep terrain. Loose snow can easily knock a person off of their feet or take them for a ride over a cliff or into a terrain trap. Manage your ‘sluff’ by letting loose snow move past you and avoid terrain features with high consequences. 


Additional Concern

Today at Treeline (the 1,000’ – 2,500’ elevation band) on all aspects, pay attention to and avoid glide cracks. These can lead to glide avalanches that are very unpredictable as we have seen over the past few days. There is no discernable pattern to predict a failure as they tend to fail naturally and on their own schedule. Warm temperatures can trigger them and so can cooling temperatures. Cracks can form and release in seconds or days later or sometimes a glide crack won’t release at all. The new snow has made it harder to see the existing cracks and glide releases in the terrain. 

It is best to give glide cracks a wide berth.  Avoid spending time underneath and if skiing or riding in terrain with glide cracks, try and map them out before your travels so as not to end up directly on top of or inside one.  Remember, when these do fail, they tend to be destructive, failing to the ground and bringing the entirety of the snowpack with them. 

Close up comparision of a glide crack on the East face of Seattle Ridge that released suddenly on Jan.16. These glide releases are now covered with fresh snow and harder to see. 

 


Mountain Weather

Yesterday 5” of new snow was recorded at Center Ridge weather station. Temperatures increased into the low 30’s F at 1000’ causing wet heavy snow to fall along the road. Ridgetop winds were light from the Northeast.

Overnight precipitation stopped and temperatures cooled into the high 20’s.

Today expect valley fog in the morning. Skies are expected to be mostly cloudy. There’s a chance of light snowfall by early afternoon. Expect temperatures to increase into the low 30’s F and wind to be light from the Northeast.



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 30  0.5  88 
Summit Lake (1400') 31  27 
Alyeska Mid (1700') n/a  n/a  n/a   n/a  

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  NE  14  44 
Seattle Ridge(2400') 26  n/a   n/a   n/a 

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: Apr 11, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: OpenWide swaths of open river in the Placer Valley. Travel with extreme caution!
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: ClosedClosed for the remainder of the 2017 season.
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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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
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