Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, January 20th, 2017 - 7:00AM
Expires
Sat, January 21st, 2017 - 7:00AM
Forecaster
Wendy Wagner
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!!

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Fri, January 20th, 2017
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
Low (1)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

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.

Avalanche Problem 2
  • Dry Loose
    Dry Loose
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
More info at Avalanche.org

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
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

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.

Weather
Fri, January 20th, 2017

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′) 5   0   0   41  
Summit Lake (1400′) -4   0   0   14  
Alyeska Mid (1700′) 4   0   0    39

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 5   NW   8 27  
Seattle Ridge (2400′) 7   NW   12   45  
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Riding Areas
Updated Wed, December 11th, 2019

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area Status Weather & Riding Conditions
Glacier District
Johnson Pass
Closed
Closed.
Placer River
Closed
Closed.
Skookum Drainage
Closed
Closed.
Turnagain Pass
Closed
Closed.
Twentymile
Closed
Closed.
Seward District
Carter Lake
Closed
Closed.
Lost Lake Trail
Closed
Closed.
Primrose Trail
Closed
Closed.
Resurrection Pass Trail
Closed
Closed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor
Closed
Closed.
South Fork Snow River Corridor
Closed
Closed.
Summit Lake
Closed
Closed.

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