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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Monday, January 12th 2015
Created: Jan 12th 6:16 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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'
 Show the Complete North American Avalanche Danger Scale
The Bottom Line

Today the avalanche danger is MODERATE at treeline. Unusual spring-like conditions are causing an upside down danger rating. Today .21 inches of rain is expected up to 3500’; increasing the likelihood for wet avalanches and glide avalanches below 2500'. At higher elevations where cooler temperatures have formed a firm supportable crust the avalanche danger is LOW in the Alpine.

Over the last two days several natural glide avalanches have occurred and many glide cracks have grown in size. (See photos below) In general it is best to avoid traveling under or near these large frowning cracks.


Primary Concern

Over the last 4 days we’ve seen unusually warm temperatures above freezing at lower elevations, which has caused a lot of water to flow through the snowpack. Yesterday morning several glide avalanches were observed on the Eastern face of Seattle Ridge and the Southern face of Eddies, all below 2700'.  Today rain is expected throughout the day increasing the potential for more glide activity.

Glide avalanches are common to Alaska’s maritime snowpack and occur in steep terrain where the bed surface underneath is slick. These rather unpredictable avalanches are not associated with a human trigger. They seem to happen spontaneously during prolonged periods of warming when water has lubricated the ground; as observed by a Level 2 avalanche student yesterday in a snowpit on Seattle Ridge.

In general it is best to not travel underneath or in terrain where glide cracks have formed. Fortunately they seem to be more common in steep extreme terrain and are easy to identify, thus making them avoidable.

At higher elevations there are fewer glide cracks visible, but it is still wise to plan your travel around them. 

 

Two recent glide avalanches on the Eastern Face of Seattle Ridge were observed yesterday morning. Starting zone elevation is estimated between 2500' - 2700'

 

Recent glide avalanches on Eddies South Face, elevation estimated at about 2500'. 


Secondary Concern

Today rain combined with above freezing temperatures is increasing the likelihood of wet loose avalanches at elevations below 2000’. Over the last 4 days a lot of water has drained through the snowpack causing the snow to become unconsolidated and wet at treeline. Rain today and into tonight could increase the likelihood of small human triggered wet loose avalanches on steep terrain features.

At higher elevations where temperatures have been cooler a solid melt/freeze crust has formed making this problem unlikely above 2000’.  Be aware of an area between 2000’ and 2500’ where breakable crust with moist snow below could be extra challenging to ski/ride through today.   

 

As of yesterday a very supportable melt/free crust has formed above 2500'. Notice the re-frozen rain runnels and old ski tracks on Tincan.  


Mountain Weather

After an initial rain event on Jan. 8th this warm spring-like weather seems to be sticking around into this week. Over the last few days temperatures have been in the low to mid the 30’sF with a 3-day stretch of temps averaging 35F at Center Ridge (1880’) weather station. No new precipitation has been recorded since Jan.8th.

Yesterday temperatures were mild, in the high 20’sF at ridgetops and mid 30’sF at 1000’. Skies were patchy with isolated areas of light precipitation, but no accumulation in Turnagain Pass was recorded. Winds were light in the morning and East ridgetop winds picked up to 10-25mph throughout the day.

Today another low-pressure system continues to bring unusually warm January weather. We expect to see rain starting this afternoon, up to .21 inches at Turnagain Pass. Rain/snow line will be around 3500'. East winds should increase to 25-45mph at ridgetops.

Tonight precipitation is expected to increase with up to 1 inch of water and rain/snow line is expected to remain around 3500'. East winds will continue to be 25-45mph at ridgetops. 

There is some talk later in the week of cooler air from the artic combined with moisture helping us keep our hopes up that snow may be in our future. 



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 35  0 29 
Summit Lake (1400') 33 
Alyeska Mid (1700') 35  22 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 28  13  34 
Seattle Ridge(2400') 30  ENE  14  27 

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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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