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Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, December 14th 2018 7:00 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE in the Alpine and at Treeline where triggering a slab 1-3’ deep is possible in a shallow areas of the snowpack. In the Alpine triggering an isolated windslab or getting caught up in a loose snow avalanche is possible in steep terrain. Avoid traveling underneath glide cracks.

Assess the snowpack as you travel, identify areas of concern and evaluate consequences.


 Show the Complete North American Avalanche Danger Scale
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.
Special Announcement

If you are heading to Hatcher Pass make sure to read a recent report from Hatch Peak on Sunday where a skier was fully buried and recovered without injury.  Be aware alaskasnow.org is undergoing a system-wide website update and Hatcher Pass Avalanche Center webpage may look very different when it is finished. For now stay current by following the new Hatcher Pass Avalanche Center mid-week update HERE. 

Looking for avalanche courses or evening presentations? Check out our calendar page


Avalanche Problem 1

Wind Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Overnight ridgetop winds have picked up into the teens with some gust in the 20’s mph. In the alpine there’s over a foot of low-density snow available for transport and another 3-6” of new snow in the forecast today. Triggering an isolated windslab on leeward or cross-loaded features will be possible, especially if you see blowing snow. Otherwise mild weather and cold temps have been keeping all this new snow as light dry powder. Should you go into steep terrain, pay attention to how much new snow is falling and if winds are moving it around. Shooting cracks will be an obvious clue windslabs are tender. Feel for punchy or upside down  snow and keep in mind the consequences of the terrain should even a small rug get pulled out from underneath you. In areas where winds aren’t an issue loose surface snow could move faster and farther than expected. 

Shooting crack on a wind loaded terrain feature on a NW aspect of Tenderfoot yesterday at 2500'. 

 

Some larger fast moving point release sluffs were observed yesterday in steep terrain on Sunburst. 


Avalanche Problem 2

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

No new avalanche activity has been reported in our forecast zone since a wet and windy storm ended last weekend. Yesterday dozens of tracks could be seen in steep terrain which is a good sign of increasing stability. With that said there remains some uncertainty around weak snow within older layers of the snowpack, especially in Summit Lake, in Crow Creek Valley and the Southern end of Turnagain Pass where a thinner snowpack exists. The mid-elevation band is also more suspect where the snow quickly transitions to shallower depths. Observations this week have found a facet/crust combo 1-2’ below the surface in the mid-elevations (2000’ – 2700’.) Whumpfing and reactive stability tests were observed on Tuesday on Magnum’s NW shoulder. Rotten faceted snow near the ground in Summit Lake  is also a concern especially with more snow expected over the weekend. Evaluated the snowpack and terrain as you travel and be aware that obvious clues like whumpfing or recent avalanche may not be present.

Snowpit on Tenderfoot shows a thinner snowpack where weak snow is sitting on the ground. 


Additional Concern

Glide Avalanches

The first glide cracks of the season were seen on Sunburst SW face under the weather station and another on the SW face of Tincan Proper. A glide crack is the snowpack being pulled by gravity downhill along the ground. They can release at any moment without warning and are usually not associated with human triggers. The best way to manage this hazard is to avoid being on or beneath any slopes with cracks opening up. 


Mountain Weather

Yesterday: Skies were clear and sunny. Temperatures were in the single digits (F) in the upper elevations and teens (F) near 1000’. Winds were light and picked up in the evening from the East 10-15mph with gusts in the 20s mph. An inch of new snow fell in Turnagain Pass overnight and a trace in Girdwood.

Today:  Temperatures will gradually increase throughout the day into the mid-20’s at 1000’. Snow showers will start this afternoon with 3-6” of snow possible and another 4-5” overnight. East ridgetop winds are expected to be 10-15mph and build into the 20’s mph overnight.

Tomorrow: Temperatures will continue to increase into the mid-30’s (F) at sea level. Rain/snowline may be around 500’. Another storm is expected Saturday evening through Sunday morning. An active weather pattern is expected to persist into early next week.

*Seattle Ridge weather station anemometer has been rimed and not recording wind data.   

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 13  0.1  31 
Summit Lake (1400')
Alyeska Mid (1700') 14  trace  0.07  17 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') ENE  31 
Seattle Ridge(2400') 12  *NA  *NA   *NA  

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 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
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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