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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Tuesday, March 8th 2016
Created: Mar 8th 6:31 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.
0 NO RATING Below Treeline / Below 1,000'
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The Bottom Line

The avalanche hazard is MODERATE today above 1,000’.  Glide cracks continue to pose a very real and serious threat to a substantial amount of terrain frequented by skiers and snowmachiners in the mid-elevations.  Above treeline, surface instabilities such as shallow wind slabs and loose snow sluffing make up the secondary concern today.

Cornices deserve mention as well as they loom precariously over a lot of well-travelled terrain and have been releasing as recently as yesterday.


Primary Concern

We’ve seen 2 new glide cracks 'pop' in the last 24 hours, and several others in the past week.  Though incredibly unpredictable as to when these cracks may avalanche, we have noticed that some cracks are growing in size and are showing their ugly faces once again, allowing us to map them out and plan travel accordingly.  It’s an easy avalanche problem to mitigate; simply avoiding time spent exposed under these yawning cracks.  Though the probability of tangling with a glide in motion is low, the consequences will be fatal if you are in the wrong spot at that moment when stress overcomes strength and a glide crack turns into a glide avalanche.

If you’re a daily reader of this advisory you’ll notice this is the 61st day in a row where we’ve made mention of glide avalanches, unfortunately there is no end in sight.  It’s been an unusual season in this respect and as the old-timers say; unusual conditions breed unusual avalanches.

An unmistakable example of the avalanche problem we are dealing with reared it's head yesterday morning, just outside of the motorized parking lot (East face of Seattle ridge).  The crown on this full-depth glide avalanche is easily 10 feet deep.

 

Oblique view of the same glide as above, looking south toward Johnson Pass and Lynx creek.


Secondary Concern

Shallow wind slabs (6-10”) were proving reactive to skiers on Sunday after a bump in Easterly winds Saturday.  With another slight bump yesterday (gusting to the mid-30’s mph on Sunburst), we could continue to see some shallow wind slab activity in the upper elevations.  Key in to any cracking, wind-textured or stiffer surfaces to suss out a wind slab.  No consequence test slopes will be a valuable tool today to get a better idea of reactivity and average depth of wind slab we’re dealing with.

Loose snow:

Loose snow sluffing will warrant management today if skiing the steeps.  Sluffs have been reported to be fast moving with the ability to entrain a significant amount of surface snow in big terrain.  This will be more pronounced on cooler, shadier North aspects.


Additional Concern

Listen to your Mother’s voice in your head and “stay away from the edge.”  Take her advice and double it to give yourself a wider berth than you AND your Mother think necessary.  Furthermore, be very wary of spending time beneath cornices.  A group yesterday heard/ witnessed a large cornice failure off the S face of Kickstep during the heat of the day (2:30pm).  These are becoming larger and weaker, ebbing closer to the point of failure as we move in to Spring.


Mountain Weather

Greybird was the word in Turnagain pass yesterday.  Skies were overcast with just a trace of moisture falling.  Temperatures averaged 32F at 1,000’ and winds were in the low teens gusting to the mid-30's from the East on ridge tops. 

Today looks to be almost a carbon-copy day of yesterday.  High clouds are streaming in from a well-developed Low centered in the Gulf of Alaska.  Temps will be in the mid-30’s at 1,000’, ridgetop winds are expected to be in the teens or less from the East and precipitation will be nominal through Turnagain Pass. 

Tomorrow we may have a weak ridge move over the eastern Turnagain arm area promoting partly sunny skies before the our next chance of active weather on Thursday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  32  1 .1  136 
Summit Lake (1400') 34  43 
Alyeska Mid (1700')  32  0 .05  106 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24   NE 10  34
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: Dec 08, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedRain and snow have fallen in Turnagain Pass this week, but not enough to open for snowmachining. Continue to check back to this site for updates.
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to 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
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