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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Wednesday, March 26th 2014
Created: Mar 26th 6:40 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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.
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The Bottom Line

The avalanche danger remains LOW this morning on all aspects and elevations.  Warming temperatures and direct solar input on large cornices and southerly slopes may increase the danger to MODERATE where wet point release avalanches and cornice failure may initiate late in the day.  

Low danger does not mean no danger! Good travel habits remain important.  These include exposing only one person at a time on a slope, watching your partners closely and having an escape route planned in case the snow moves or a cornice fails.


Primary Concern

High pressure and mild temperatures continue to dominate much of our State.  This ‘lack of weather’ over the last week and a half has contributed to a stabilizing trend in the snowpack that has been afforded ample time to adjust to our most recent winter storm (March 10-14th).

Specific hazards one may experience when travelling into the backcountry today include threatening cornices, wet loose avalanches late in the day, shallow wind slabs or an unlikely but very dangerous persistent slab.  Furthermore, surface conditions are quite variable throughout the backcountry right now.  Read here and here for a couple different accounts of a heinous fall (but positive outcome) a snowboarder took on Sunday in the Chugach range.

Cornices: 

Perhaps the most unpredictable problem today, we’ve seen evidence in the last week of natural cornice failure that have subsequently triggered slab avalanches.  This is the type of large trigger likely needed to wake up a persistent slab that could result in a large and destructive avalanche.  Your best mitigation tactic for cornices is to recognize them and limit exposure on top of or underneath these bulbous snow formations, particularly late in the day when solar input is greatest.

Wet loose avalanches: 

We saw evidence yesterday on the sunny side of Turnagain Pass where wet-loose avalanches or point-releases initiated and ran several hundred feet.  Though not a huge problem on their own, this is the type of small slide that can get you into big trouble if above a terrain trap or in complex, “no-fall” terrain.  It’ll be best to avoid steep, southerly aspects late in the day once you begin to notice the snow surface will no longer support your weight off your skis or sled.

Wind slab and persistent slabs:

Older wind slabs from last week may still be lurking in untested terrain today.  With people pushing further out into the periphery and skiing bigger, more committing lines over the last week the possibility of triggering an older, stiff wind slab exists. 

A note on persistent slabs:  The nature of this avalanche problem is persistent.  Though unlikely to trigger today, we know that weak snow layers do exist 2-5’ deep and a resulting persistent slab avalanche would likely be un-survivable.  To mitigate this problem, follow safe backcountry travel protocol that includes wearing and knowing how to use rescue gear and exposing only one person at a time on a given slope.  


Mountain Weather

Clear blue skies, light wind and warming temperatures yet again dominated our environment if you were so lucky to venture outside yesterday.  Ridgetop winds were light out of the east and temperatures averaged in the mid-20’s at these upper elevations.  At sea level locations and in valley bottoms cold air-pooled to create a decent temperature inversion yesterday morning.

Today looks to be a similar set-up as yesterday with the rising sun breaking up that inverted layer (8 deg at Granite campground this morning and 24 deg at Sunburst weather station) by mid-day and temperatures steadily climbing into the low 40’s at 1,000’.  Winds have shifted slightly to a westerly direction but look to be light and variable all day.

It looks like this stubborn blocking high pressure is here to stay well into next week as clear skies will continue to support warmer than normal high temperatures and below normal lows overnight.

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 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
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: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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