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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Tuesday, January 26th 2016
Created: Jan 26th 5:32 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
Special Announcement

There have been ten people killed in avalanches in the United States since January 16. Fatalities have occurred in Colorado, Utah, Wyoming, Montana, Washington, and Alaska. This in the largest number of US avalanche fatalities in January since at least 2001. More info and preliminary reports on all of these acidents can be found at Avalanche.org.


The Bottom Line

There is a MODERATE avalanche danger today above 1,000’ in the mountains surrounding Turnagain pass.  Fresh wind slabs 6-12” thick will be possible to trigger in steep terrain on leeward (wind-loaded) sides of ridges in the alpine.  In the treeline elevation band (1,000 – 2,500’) an overabundance of glide cracks are keeping the danger pegged at MODERATE as these may release spontaneously and without warning.

Below treeline the danger is LOW as unfortunately, we lack snow to have much of an avalanche problem.

Take a look at the Summit Lake snow and avalanche Summary as well as recent observations from the Summit Lake zone if your plans have you skiing further South of Turnagain pass today.


Primary Concern

Surface instabilities in the form of fresh wind slabs make up the primary avalanche concern today.  With more wind than precipitation yesterday in the Turnagain pass area we can expect to find wind slabs in the 6-12” range on wind-loaded and cross-loaded slopes above treeline.  As these last couple of storms have come in quite warm, wind slabs appear to be adhering well and may be stubborn to initiate.  Very steep, wind-loaded terrain may be the exception.  Overall, across the Turnagain pass zone (and above about 2K), the snowpack is deep and is lacking any reactive persistent weak layers.  Aside from glide cracks (more info below) any instability today should be relegated to the top 12-18” of our snowpack.  You can quickly test for surface instability by conducting hasty hand pits or jumping on (no consequence) test slopes with your skis or machine. 

Cornices deserve a note as well, as these warm, windy storms prove ideal to continue to add to their mass.  Avoid time spent below and when travelling along a corniced ridge, whether on skis or snowmachine maintain a healthy distance (and then some!) from the edge.  

Note: The Girdwood Valley recieved about twice as much water (.9") as Turnagain pass yesterday.  If venturing into the upper elevations around Girdwood, fresh wind slabs and storm slabs are likely to be thicker.  


Secondary Concern

Visibility yesterday limited a look at many of the glide cracks that we’ve been monitoring over the last 2-weeks, including a behemoth on the SW face of Corn Biscuit.  If someone were to tangle with a glide avalanche, it would simply be a ‘wrong place at the wrong time’ scenario.  It’ll be best to limit or avoid altogether time spent underneath glide cracks and recognize them for the dangerous, unpredictable avalanche problem that they are.

This photo is of a very large glide crack as observed last Thursday, 1/21.  Yesterday, visibility was too poor to see if this had progressed anymore toward failure but see Wendy's obervation from 1/24.  She was able to see visible changes in this crack over an hour timespan.  

 

Another concern today in this mid-elevation band comes in the form of wet-loose avalanches as the snowpack is quite heavy and wet below 2,000'.  With continued warmer than normal temps and a slight chance of a few rays of sun today, we may see some wet-loose and/ or roller ball activity in steep, mid-elevation terrain.  


Mountain Weather

A low ceiling and steady precipitation around eastern Turnagain arm dominated yesterday’s weather. Temps were hovering around 34 F at 1,000’ (37 F at sea level) with a rain/ snow mix at the Turnagain pass parking lots and the rain-snow line around 1,300’.  Ridgetop winds were moderate from the NE averaging in the 30’s and gusting to 63 mph before tapering off a bit overnight.  Center ridge SNOTEL site (1880’) picked up a couple inches of snow (.4” water) in the last 24 hours while Girdwood picked up .9" of water as reported at the Alyeska mid-station. 

Today looks to be a slight break in our active weather pattern before another Low and associated front rolls through southcentral AK tomorrow morning.  Temperatures are expected to be in the mid-30’s at 1,000’ with ridgetop winds from the East in the 10-25mph range.  Skies will be mostly cloudy but we shouldn’t expect to see more than an inch or two of snow wrung out today in favored areas of the Pass.  

More unsettled weather is on tap as we head toward the weekend with the big quetion being precipitation type and just where that rain/ snow line will fall.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 32   2 .4  92 
Summit Lake (1400') 33   1 .2  28 
Alyeska Mid (1700')  33  0 .9  73 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  26 ENE  28  63 
Seattle Ridge(2400')  28 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: Mar 25, 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: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
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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