Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, February 3rd, 2017 - 7:00AM
Expires
Sat, February 4th, 2017 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

A generally LOW avalanche danger exists in the mountains surrounding Turnagain Pass.  Point release avalanches triggered by the sun and/or humans on steep slopes with a Southerly tilt will be possible again today. Cornice falls are also possible, and occurred yesterday, with the warm sunny weather. Watch for winds that may pick up today to form soft and shallow wind slabs on leeward slopes. Lastly, triggering a large avalanche breaking 2-4′ deep in weak snow deeper in the pack is unlikely but not out of the question.  

Girdwood Valley:   A MODERATE avalanche danger exists in this area due to a thinner snowpack with weak snow found near the base. The possibility exists for large avalanches, breaking near the ground, to be triggered in thin areas and/or remotely from ridgelines or the bottom of slopes.

Placer Valley, Johnson Pass and areas  South of Turnagain Pass:   There is a  MODERATE  avalanche danger in these areas as well for large slabs breaking near the ground. We have little information in these zones, but we do know there is weak snow near the base of the pack, similar to the Southern Kenai and Girdwood Valley.

Summit Lake:  An unstable snowpack exists in the Summit Lake area and similar to the regions above, human triggered avalanches breaking near the ground are possible. Make sure and check the Saturday Summit Summary  HERE.

** It will be critical to carry rescue gear and maintain  safe travel protocol this weekend – such as exposing one person at a time, grouping up in safe zones, having escape routes planned and watching your partners!

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Fri, February 3rd, 2017
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
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
Moderate (2)
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
  • 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

It’s that time of year! The sun is out and affecting the snow in terrain on the Southern half of the compass.  With 4-8″ of loose snow on the surface over a dense base, watch your sluffs and watch how the sun is affecting the snow around you.  

Wind Slabs? There is a slight chance winds could bump up enough to form soft shallow slabs on leeward slopes. Although the main flow will be Northwesterly, loading Southeasterly aspects, this pattern also creates a Southerly flow along the East side of Turnagain Pass which loads North aspects (such as Sunburst and Tincan). 

Avalanche Problem 2
  • 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

With February already here along with a high pressure stint bringing sunshine, it may be easy to forget many areas in Southcentral have a poor snowpack structure. As mentioned in the bottom line above, weak snow near the base of the pack exists on slopes with a thinner snow cover. The heart of Turnagain Pass has drawn the lucky ticket and the pack is deeper and stronger with avalanche concerns focused on surface instabilities (sluffs and shallow fresh wind slabs). 

If deciding to venture to the periphery zones, watch for recent avalanche activity, listen for whumphing (collapsing of the snowpack) and cracks that shoot out from your snowmaching, skis or snowboard. There also can be no warning signs before an avalanche is triggered. This type of avalanche is often triggered in a thin spot, near rocks or on the edge of the slab. These can also be triggered by large groups and/or snowmachines on, near or under slopes. Again it will be critical to maintain safe travel protocol, again as mentioned above.

 

 

Additional Concern
  • Cornice
    Cornice
Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Cornice falls are possible with warm temperatures and sunshine. These could release naturally and be near the tipping point that person breaks them off easily. Keep a wide berth when on ridgelines and limit time underneath. 

 Photo: Cornice fall yesterday in Warmup Bowl in the Seattle Creek drainage. Triggered from a person on the ridge later in the day.

Weather
Fri, February 3rd, 2017

It was a brilliant sunny day in the mountains yesterday with little to no wind at all elevations! Temperatures were cool (~10-15F) in valley bottoms and warmer (20-30F) on the ridgelines.  

Today will be much of the same with two slight changes, but first, bring your dark lenses as the sun will be intense. 1) Ridgetop winds have just bumped up slightly this morning and could be breezy for the day (5-15mph from the North and West, gusting 10-20mph). Temperatures have climbed overnight at the high elevations and sit around 32F – valley bottoms have decreased and sit in the single digits… Another blocking high-pressure and associated stout inversion is settling in…

These conditions are expected to persist all the way through the weekend and into Monday. There’s no hint of a storm cycle in the foreseeable future, but we could get some flurries the middle part of next week.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 19   0    0 55  
Summit Lake (1400′) 10   0    0 24  
Alyeska Mid (1700′) 21   0   0   49  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 29   W   3   16  
Seattle Ridge (2400′) 24   NE   3   10  
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Riding Areas
Updated Mon, December 02nd, 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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