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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Monday, February 15th 2016
Created: Feb 15th 6:36 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.
0 NO RATING Below Treeline / Below 1,000'
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Special Announcement

Do you frequent Hatcher Pass? Mark your calendars!

Wednesday, February 17th a FREE Avalanche Awareness Class hosted by Hatcher Pass Avalanche Center in partnership with F-CNFAIC and the Hatcher Pass Mountaineering Huts Group. Join CNFAIC Avalanche Specialist Aleph Johnston-Bloom at the Palmer High School Library from 6:30-8pm. 

Saturday, February 20th Hatcher Pass Avalanche Center is having their annual fundraiser at Gov’t Peak Chalet near Hatcher Pass. This event will feature a slide show by local climber and ski mountaineer, Kirsten Kremer.  Click HERE for more info on both events.


The Bottom Line

Following a three-day storm a MODERATE avalanche danger exists in Turnagain Pass. In the Alpine (above 2500’) be aware of very large cornices and lingering wind slabs 1-2’ thick on leeward terrain features. At treeline glide avalanches continue to threaten large amounts of steep real-estate on all aspect below 2500’. The travel advice for glide cracks and cornices are similar, avoid being on or under either, both are extremely unpredictable. Should sky cover clear earlier than anticipated today, pay attention for warming daytime temperatures and sun induced wet-loose activity at all elevations.

*Shallow snowpack zones: South of Turnagain Pass and the Summit Lake area. These areas have old weak layers in the snowpack that have received additional weight and stress from wind, warm temps, and precipitation. This is something to keep in mind if you are headed to these zones this week with the expected clear skies. 


Primary Concern

Wind Slabs: Over the last three days moderate Easterly winds and heavy snowfall have loaded leeward terrain features above 2000’. Today light winds and a trace of new snow is expected. Should visibility allow for travel into the upper elevations, be aware of lingering wind slabs in steep terrain. Expect slabs to be 1-2’ thick and watch for cracking in the new snow. Hand pits and jumping on small terrain features and test slopes can be good ways to see how well slabs are bonding. 

Cornices: Cornices have been growing to enormous sizes and will be tender today. Steer clear and don’t put yourself directly on or under a cornice. They can break much further back along a ridge than expected and their extra large size has the potential to trigger a lingering wind slab below. 

A Cornice that has formed along "CFR" ridge above Common Bowl on Tincan, estimated to be ~15' tall. The biggest its been all season. 


Secondary Concern

Warm temps, rain and wet snow have been adding weight and stress to glide cracks throughout Turnagain Pass. These unpredictable hazards cover many steep slopes between 1000’ to 2500’ and continue to release without warning. Look for the large upside down ‘brown frowns’ and avoid hanging out directly underneath glides. Several glide cracks have released in the last few days including a new one on Sharks Fin.

Seattle Ridge is covered in large glide cracks that span most of the East Face along Turnagain Pass. 

 

Southwest face of Sharks Fin as seen from the Seward Hwy yesterday. Exact timing of this glide avalanche is unknown, but likely in the last two days.

 

 


Additional Concern

Freezing overnight temperatures are helping the lower elevations form a light crust and water continues to drain from a saturated snowpack below 1500’. Today daytime temperatures may reach the mid 30’s and wet loose avalanches will be something to monitor. If the snow is wet and slushy avoid steep terrain where loose wet snow has the potential to gain momentum and entrain deeper into the snowpack.

*Isolated snow and rain showers are in the forecast for today, but should the sun find its way through the clouds, be on the look out for wet loose activity in the mid to upper elevations. I know… this seems a little premature, but since the surface snow is light and dry, it doesn’t take much solar exposure to affect new snow. 


Mountain Weather

Yesterday temperatures cooled to 32F at Turnagain Pass and light snowfall was observed during the day. Visibility was mostly obscured with a few periods of broken skies.  Winds were light from the Northeast and ridgetop winds averaged in the low teens (mph.)

Overnight temps remained just below freezing and no new precipitation was recorded. In Girdwood light rain stopped around midnight and winds remained light from the Northeast.

Today scattered rain and snow showers are expected. Temperatures could rise into the mid 30’s F with light rain to 1500.’ Winds will be light from the Northeast and sky cover could clear off enough to see patches of sun by late afternoon. 

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31  trace  0.1   101
Summit Lake (1400') 33  30 
Alyeska Mid (1700') 32  0.39  87 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  ENE  11  49 
Seattle Ridge(2400') 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: 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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