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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Saturday, February 7th 2015
Created: Feb 7th 6:37 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.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
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The Bottom Line

The avalanche danger is LOW in the Treeline and Alpine elevations today.  Isolated pockets of 6-8” wind slab may be encountered in the highest elevations around the Girdwood Valley.  It is in these isolated areas, on the periphery of the forecast zone, where the danger is MODERATE.


Primary Concern

It has now been three weeks since the snowpack received any significant load.  In those three weeks a total of 4” of snow fell in 1” increments.  Temperatures have remained seasonable and winds have for the most part been calm.

What this all adds up to is a snowpack that is generally well adjusted.  Triggering an avalanche is possible, but falls into the “outlier” category. 

Low volume loose snow avalanches can be triggered on very steep (>40 degrees) sustained slopes.  Watch your sluff and steer away from it, especially around terrain traps. 

Isolated pockets of recently formed wind slab 6-8” in depth may be found in the higher elevations around the Girdwood Valley.  If you make it into these areas, be on the lookout for stiff and hollow sounding snow on steep leeward slopes.

Glide cracks are scattered throughout the forecast area.  Minimize time spent under glide cracks as they can release without the normal warning signs.

Aside from these snowpack issues you can expect to encounter firm and icy conditions on approaches (see photo below) with rocks and stumps being obstacles to avoid while exiting the mountains.

Icy Tincan approach


Mountain Weather

A much anticipated wind event for Southcentral AK took place over the last 24 hours.  Fortunately Turnagain Pass was spared in this outflow event.  We found winds to be calm on ridgetops while in the field yesterday.  Light plumes coming off of the higher peaks around the Girdwood, Twentymile, and Portage Valleys could be seen occasionally during the day.

Wind in mountainous terrain is not straightforward. Pictured here are plumes coming off a peak above Twentymile from North winds on Feb 6th. The wind anemometer at sea level shows winds out of the South. photo: Fitzgerald

Wind??

Temperatures were cold, with ridgetops averaging in single digits F.

Today will be a cold one, with temps to remain in the single digits F at ridgetops.  Winds will be light out of the North at 5-10mph.  We may see some high clouds streaming in from the East as a result of Low pressure spinning in the Gulf of Alaska.

The extended outlook is showing a welcome change in the overall pattern.  High pressure that has dominated lately will break down and allow for moisture to make its way to the area.  The next chance for accumulating snow will come by Tuesday or Wednesday of the coming week.

*Alyeska Mid station data 7am-2pm due to station malfunction.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 12 0 0 31
Summit Lake (1400') 0 0 0 7
Alyeska Mid (1700') 10 0 0 21*

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 6  ENE 7 23
Seattle Ridge(2400') 9 S 4 17

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

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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
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