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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Saturday, December 10th 2016
Created: Dec 10th 4:45 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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
Tesoro Foundation
Special Announcement

Mark your calendar for next week's Fireside Chat: Avalanche Awareness and Rescue w/CNFAIC in Girdwood at the Powder Hound Ski Shop!
December 15 @ 6:30 pm - 8:00 pm. FREE.  Join CNFAIC forecasters for an evening of avalanche awareness with a focus on recognizing obvious clues to instability and companion rescue.

**Planning on taking an avalanche class? The Friends of the CNFAIC is offering two avalanche scholarships through the Rob Hammel fund. Both scholarships are for $500. One is for avalanche professionals and the other is open to anyone!  The deadline for both scholarships is Dec 15th! For more information click this link HERE


The Bottom Line

A generally LOW avalanche danger exists across all elevations bands for the Turnagain Pass zone. Triggering a 1-2' avalanche is unlikely but not impossible. The most suspect slopes are in steep terrain at the high elevations where someone just might be able to break off an old wind slab or find a slope with the buried surface hoar that hasn't slid. Good travel habits, such as exposing one person at a time, watching your partners and grouping up in safe zones are, as always, key ways to minimize risk. Ease onto steep slopes and be mindful of people below you and on adjacent slopes.

There is snow to sea level and amounts have been adding up enough to put a LOW danger rating on the Below Treeline Elevation band. Portage Valley received 6-8" of snow yesterday. This should be part of the equation if you are heading to ice climb this weekend, a small slide could have high consequences.

*If venturing into the 'periphery' forecast zones, such as Girdwood Valley or out of the core Turnagain Pass terrain, more caution is advised due to limited information about the snowpack in these areas. 

If headed to Summit Lake check out the Saturday Summit Lake Summary HERE 


Primary Concern

It has been a week since we had any report of human triggered avalanche activity and observers are not reporting signs of instability. As a mostly calm, clear and cold weather pattern dominates our area and continues into next week, we are in the "normal caution" phase of avalanche issues. These include:

1- Triggering an outlier avalanche. This would most likely be an 'unsupported slab' that sits above a cliff or steep rocky terrain. More specifics below in the concerns.

2- Triggering a cornice fall. The cornices maybe be small right now, but they are large enough to take you down somewhere you don't want to go. As always, give them a wide berth.

3- Sluffs on steep slopes. These have yet to have been observed as a problem but as the surface becomes weaker under clear skies the potential will increase. 

Remember LOW hazard doesn't mean NO hazard! It is still important to look for signs of instability and use good travel techniques. 


Secondary Concern

Even with LOW avalanche danger it is still important to remember the weak layer 1-2' below the surface i.e. the notorious Nov 16th buried surface hoar. Although we have not seen an avalanche release in this layer since last Saturday and the slab character has been changing due to the cold temperatures, there are many slopes away from the 'popular' zones that have yet to be tested. These are the areas most suspect over the weekend. Finding the spot that harbors this weak layer, still has a slab and hasn't been skied or slid already still could be dangerous... Triggering is unlikely but not impossible! 

 

 Buried surface hoar in a pit on Sunburst, December 6th. SW, 3200'


Additional Concern

Several wind events over the last two weeks have formed wind slabs near and below ridgetops on a variety of aspects.  Old stiff supportable wind slabs in thin rocky areas may pop once you are out onto the slab. Be wary of hard over soft snow, hollow sounds and steep slopes with obvious deposition in the start zone.


Mountain Weather

Yesterday was mostly clear above the valley fog, which crept higher as the day progressed. Temperatures were in the low 20Fs and decreased through day. Winds were light and variable. Overnight temperatures dropped into single digits in the valleys and were in the teens up high. The wind speeds bumped into the teens gusting into the high 20s from the east.

Today will be cold and clear with light easterly winds shifting to north in the afternoon. Tonight and tomorrow look very similar with temperatures getting colder through the weekend. Single digits to mid teens should be expected. This weather pattern dominates into next week. Look for a potential shift with warmer temperatures and a chance of precipitation later in the coming week. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  19  0 21 
Summit Lake (1400')  13  0  0   4
Alyeska Mid (1700')  22  0  0  11

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  18 variable   7 27 
Seattle Ridge(2400')  21 variable   6  25

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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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