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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Friday, January 9th 2015
Created: Jan 8th 22:16 pm
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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Silverton Mountain Guides
Special Announcement

Do you ski or snowmachine in Hatcher Pass?  The Hatcher Pass Avalanche Center (HPAC) and the Alaska Avalanche School (AAS) are leading an Observer’s Workshop for backcountry enthusiasts who are interested in submitting snow and avalanche observations to the HPAC.  More info can be found by clicking here.


The Bottom Line

Today the avalanche danger is MODERATE at both Treeline and in the Alpine. Small human triggered wet avalanches are possible on very steep slopes and wind slabs 1-2' deep could be found at elevations above 3500’. Avoid steep slope angles and in general be careful – the snow conditions are relatively poor and also ripe for non-avalanche related injuries. 


Primary Concern

In the last 24hours a low-pressure system has brought us very warm temperatures (40’sF) at sea level and rain to 3000’. In Turnagain Pass .5” of water was recorded and double that amount in Girdwood.

No avalanche activity was reported or observed yesterday, but today small wet loose avalanches are the primary concern in areas where low-density snow is poorly bonded. Rain saturating the snowpack can cause this type of snow to weaken and fail, more easily than in denser snow.

It is important to understand that our current snowpack is comprised of large areas of dense supportable snow in the Alpine, but pockets of weaker snow do exist. Triggering a wet loose avalanche requires a steep slope (>40°) and could be larger on sustained slopes. Today this problem will be more likely at mid elevations where there are greater areas of low-density snow.

Expected this type of avalanche to be slow to initiate, meaning they take a little time to gain momentum. Use caution if you choose to ski/ride in steep terrain today.  This kind of avalanche problem is wet and heavy and can easily grab your ski/board and pull you down.

Today light precipitation (0.1”) is expected throughout the day and rainline may decrease to 1000’. This is not enough precipitation to increase the likelihood of natural avalanches. 


Secondary Concern

At higher elevations, above 3500’, where snow has accumulated there is potential for wind slabs. Yesterday ridgetop winds were from the East and averaged 30mph. Avoid wind loaded leeward slopes if you venture above 3500’. Small pockets 1-2’ deep could be found on leeward sides of ridges and along terrain features such as gullies.

Luckily today with marginal weather and poor surface conditions this terrain will not be very attractive to ski/ride.  In fact your day might be better spent tuning your skis with a warm colored wax and saving gas money in hopes of improved conditions in the coming days. 


Additional Concern

We have been tracking several types of buried weak layers over the last three weeks. Recent loading in the last 24hours in the form of rain combined with warm temperatures could be adding additional stress. A persistent slab is more likely to be triggered on very steep slopes and in places with a generally thinner snowpack like the Summit Lake area. This problem is becoming a bit of an outlier, but we do feel it is worth keeping in the back of your mind if you are thinking about venturing onto sustained steep slopes. 


Mountain Weather

Yesterday a warm low-pressure system brought us temperatures into the 40’s F at sea level and rainline was near 3000’. Ridgetop winds were predominantly from the East averaging 30mph and .5 inches of rain was measured in Turnagain Pass and just over 1” in Girdwood.

Today warm temperatures and very light rain will persist throughout the day. Rainline may creep down to about 1000’, but only a trace of new snow is expected to fall at higher elevations. Ridgetop winds are expected to be 20- 40mph from the East.

Warm temperatures and light precipitation will continue into the weekend with our next chance for cooler temperatures on Saturday night. Winds should be light to moderate from the East. 



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 38  0.5  30 
Summit Lake (1400') 37  0.5 
Alyeska Mid (1700') 37  1.17  23 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 31  29  64 
Seattle Ridge(2400') 33  ENE  26  58

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

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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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