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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Saturday, December 17th 2016
Created: Dec 17th 5:59 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
 Show the Complete North American Avalanche Danger Scale
Bear Tooth Theatre Pub & Grill
Special Announcement

What are you doing Tuesday night?? Come to the Blue & Gold Boardshop for a CNFAIC presentation on the 'Turnagain Pass snowpack'!! This will be an interesting discussion considering the interesting snowpack! Details on link.

Motorized use:  The Chugach National Forest is monitoring snow coverage across the Forest daily for a motorized opening. A 36” base is a general number the Forest uses to determine adequate coverage - this could be more or less depending on snowpack density. Thanks for your patience and don't let up your snow dance….. The forecast looks promising!  With an opening on the horizon, have you got your rescue gear out, practiced?? Check out this successful rescue a couple days ago in Colorado.

For Hatcher Pass avalanche conditions see their Saturday advisory HERE.


The Bottom Line

There is a HEIGHTENED MODERATE avalanche danger at all elevations in the mountains around Turnagain Pass. Very sensitive wind slabs have formed over the past 24 hours due to 3-7" of new snow and moderate winds. These slabs are shallow, around 4-10" thick due to the low snow amounts, but are expected to be easy to trigger. With limited snowfall data, watch for thicker, more concerning winds slabs in areas receiving more snow/wind.

It will be very important to monitor how much new snow has fallen in the area you are traveling. This will determine how thick wind slabs will be. 

AVALANCHE DANGER is expected to rise tomorrow as a powerful storm moves through.

*Ice climbers and hikers: The potential exists today, and more so tomorrow, for debris to run through gullies into terrain below 1000' in the Portage Valley; due to an avalanche occurring above. More snow and wind exists in Portage than other areas. 


Primary Concern

We have had very little snow so far in our upcoming week of stormy weather, but the snowpack is already showing its cards. Two shallow wind slabs were triggered yesterday by skiers/riders on Tincan and Eddies. These slabs were only 4-6" thick, but are so touchy because they are sitting on VERY weak faceted snow. With another 2" of new snow overnight and continued winds, we can expect today's wind slabs to be a bit thicker - and just as touchy. 

What to watch for today:

    • Look for areas where the winds have deposited snow
    • Watch for cracks in the snow that shoot out from your feet
    • Although slabs are thin and avalanches expected to be 'low volume' they can still pose a problem if you get knocked off your feet and sent into a terrain trap

Remember safe travel protocol: expose one person at a time, have an escape route planned, group up in safe zones and be aware of groups around you.

Photo below from Adam Rothman showing the shallow wind slab on Tincan. This is a classic slope for wind slab avalanches. Keep in mind, it has likely reloaded and could be ready for another release.


So what about this snowpack???  

"This is a great layer for making avalanches." Quote from Jim Kennedy, former Alyeska Snow Safety Director and current Alaska DOT Avalanche Program Director. 

What Jim is talking about is the snow surface from our two-week cold and dry spell, shown in the video below. Faceted snow is notorious for causing avalanches once it is buried - this is the EXACT set-up we have now. With only 3-7" of new snow causing low volume avalanches now, this is a pre-cursor to what is to come with additional snow in the forecast for tomorrow.

 


Mountain Weather

Yesterday saw mostly cloudy skies with a few snow flurries. Ridgetop winds bumped up and averaged in the 20-25mph range with gusts to 51mph from a Southerly direction. Temperatures warmed to 36F at sea level (ugh....), to the upper 20's at 1,000' and low 20'sF on the ridgetops.

Overnight around 2" of moist snow fell above 300' with light rain/drizzle falling at sea level. The rain/snow line looks to be around 200-300'. Snow amounts overnight for Portage Valley and the higher elevations could be in the 4-6" range. Today we should see cloudy skies and intermittent snow showers. Snowfall amounts during the day are expected to be anywhere from 0-2 inches. Ridgetop winds will be 5-10mph from a Southerly direction. Temperatures are expected to remain warm with a rain/snow line right around sea level.

The BIG news is how tomorrow's storm is going to shape up. We are expecting winds in the 50-60mph range and snowfall in the 6" to 1 foot range. Stay tuned on tomorrow's advisory!!

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 28  0.2  23 
Summit Lake (1400') 29 
Alyeska Mid (1700') 29  0.25  14 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 22  21  NE  51 
Seattle Ridge(2400') 23   22 SE  48 

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 25, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

Subscribe to the Turnagain Area Avalanche Advisory:

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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