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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Friday, January 20th 2017
Created: Jan 20th 5:22 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.
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
Roger Hickel Contracting
Special Announcement
  • TOMORROW - Join CNFAIC forecasters at the Turnagain Pass motorized lot for a FREE avalanche rescue workshop!! Grab your buddies and practice your rescue skills from 11am-12:30pm before you head out for the day! This is a great opportunity to work on companion rescue with your beacon, shovel and probe and get a little feedback. This workshop is open to everyone and anyone, novices and experts, that recreate in avalanche terrain – snowmachiners, skiers, snowboarders, kicker-builders, etc!! More details HERE.

The Bottom Line

There is a generally LOW avalanche danger at all elevations today, however there are specific areas in the Alpine that have a MODERATE danger. These are steep slopes where fresh wind slabs may form from today's increase in Southeast winds. If found, these fresh slabs are likely to be shallow, under a foot thick and near ridgelines. There are also older wind slabs to look for that formed by strong winds yesterday and the day before. These are likely to be 1-2' thick, stiff and hard to trigger - but not out of the question. Additionally, watch for sluffs in areas unaffected by winds, these could have more volume and run faster than expected.

*Periphery zones such as Placer, the Girdwood Valley and Summit Lake may have a higher likelihood of triggering a slab avalanche breaking in older weak snow. Approach terrain with a cautious mindset and be on the lookout for Red Flags like recent avalanches, shooting cracks and collapsing. Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!


Primary Concern

After strong Northerly winds damaged much of the higher elevation slopes during the last two days, there is another round of wind on tap today. However, these winds are from the Southeast and are bringing cloud cover, warmer temperatures and a chance for 2-3+" of snow tonight. Only small wind slabs were noted in the Turnagain Pass zone yesterday from the past two days, however larger natural wind slabs occurred in the Summit Lake area. No human triggered slab avalanches have been reported - only small loose snow sluffs.

Photo: Wind slab avalanche occurring naturally on Wednesday or Thursday in the Summit Lake area (East facing slope on Fresno Ridge).

 

Due to the shift in wind direction today, fresh wind slabs may form on areas previously scoured; despite the look of the photos below, there is likely enough soft snow available for transport. The terrain forces winds to blow in very different directions on specific ridgelines, so keep in mind differect aspects may have very different wind effect. New slabs today are likely to be under a foot thick and softer compared to the hard older slabs formed Wednesday and Thursday.

If you headed to the backcounty - watch for:

  1. Recent, or ongoing, wind loading on slopes (fresh wind slabs)
  2. Old stiff snow over softer snow (old wind slabs)
  3. Recent avalanches
  4. Cracks that shoot out from your snowmachine, skis, board
  5. Collapsing, or whumphing sounds

 

 

Photo:  Wind effect on Magnum's West face. You can see scouring out of older tracks along with smooth rounded areas where snow had drifted/loaded.

 

Photo:  Another wind affected Southwesterly slope in the Placer Valley, just to the North of the Skookum drainage.


Secondary Concern

Watch your sluff. Sluffs (loose snow avalanches) triggered by snowmachiners/skiers yesterday were relatively small to medium. With another night of cold temperatures loosening the surface snow, they could be large and fast enough to catch you off your guard today. 

Photo:  Repeat Offender slide path on the East face of Seattle Ridge yesterday. You can see where the Wed/Thur winds have washed the old tracks away on the upper left of photo under the new tracks. You can also see small sluffs initiated on the steepest part of the slope in the lower right portion.


Additional Concern

A variety of weak layers exist within the snowpack and vary across our region. Following the most recent snowstorm (1/13-1/16) most of the avalanche activity has been observed in the Girdwood Valley. This makes sense since this storm favored this area and left 2-3’ of snow. A handful of small, but deep (to the ground) avalanches were spotted in the alpine this week on Southern aspects of Penguin Ridge, Raggedtop, and Magpie. Triggering even a smaller persistent slab could bury a person or take you for a very unfavorable ride over rocks. If you see recent avalanche activity, experience shooting cracks, or “whumpfing” these are obvious clues that you should avoid steep slopes.


Mountain Weather

Cold temperatures and clear skies were over the area again yesterday. Valley bottoms stuck in the -15 to -5 range while ridgetops were slightly warmer, in the 0 to +10F. Ridgetop winds were strong from the NW (~30mph, gusting 50mph) yesterday morning but have died down significantly since noon yesterday. 

Today we should see clouds filter in and a chance for snowfall as a frontal band moves through from the West ahead of a cold low-pressure. Ridgetop winds are expected to kick up from the Southeast into the 10-20mph range and bring some 'relatively' warmer air. Temperatures that have climbed overnight at the upper elevations will continue to do so today and reach the upper teens. Valley bottoms should climb into the '+' single digits today as well. Light snowfall is expected to start late today with 2-4" possible tonight.

Tomorrow, the frontal band looks like it will still be over our region bringing a chance for additional light snow showers and cloud cover. Temperatures should remain warmer in the teens F with a light Southerly flow along the ridgetops. Stay tuned!

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 41 
Summit Lake (1400') -4  14 
Alyeska Mid (1700')  39

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') NW  8 27 
Seattle Ridge(2400') NW  12  45 

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 15, 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

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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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