Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, February 15th, 2016 - 7:00AM
Expires
Tue, February 16th, 2016 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

Following a three-day storm a MODERATE avalanche danger exists in Turnagain Pass. In the Alpine (above 2500′) be aware of very large cornices and lingering wind slabs 1-2′ thick on leeward terrain features. At treeline glide avalanches continue to threaten large amounts of steep real-estate on all aspect below 2500′. The travel advice for glide cracks and cornices are similar, avoid being on or under either, both are extremely unpredictable. Should sky cover clear earlier than anticipated today, pay attention for warming daytime temperatures and sun induced wet-loose activity at all elevations.

*Shallow snowpack zones: South of Turnagain Pass and the Summit Lake area. These  areas have old weak layers in the snowpack that have received additional weight and stress from wind, warm temps, and precipitation. This is something to keep in mind if you are headed to these zones this week with the expected clear skies.  

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Mon, February 15th, 2016
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
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
No Rating (0)
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

Wind Slabs: Over the last three days moderate Easterly winds and heavy snowfall have loaded leeward terrain features above 2000’. Today light winds and a trace of new snow is expected. Should visibility allow for travel into the upper elevations, be aware of lingering wind slabs in steep terrain. Expect slabs to be 1-2’ thick and watch for cracking in the new snow. Hand pits and jumping on small terrain features and test slopes can be good ways to see how well slabs are bonding. 

Cornices: Cornices have been growing to enormous sizes and will be tender today. Steer clear and don’t put yourself directly on or under a cornice. They can break much further back along a ridge than expected and their extra large size has the potential to trigger a lingering wind slab below. 

A Cornice that has formed along “CFR” ridge above Common Bowl on Tincan, estimated to be ~15′ tall. The biggest its been all season. 

Avalanche Problem 2
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Warm temps, rain and wet snow have been adding weight and stress to glide cracks throughout Turnagain Pass. These unpredictable hazards cover many steep slopes between 1000’ to 2500’ and continue to release without warning. Look for the large upside down ‘brown frowns’ and avoid hanging out directly underneath glides. Several glide cracks have released in the last few days including a new one on Sharks Fin.

Seattle Ridge is covered in large glide cracks that span most of the East Face along Turnagain Pass. 

 

Southwest face of Sharks Fin as seen from the Seward Hwy yesterday. Exact timing of this glide avalanche is unknown, but likely in the last two days.

 

 

Additional Concern
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

Freezing overnight temperatures are helping the lower elevations form a light crust and water continues to drain from a saturated snowpack below 1500’. Today daytime temperatures may reach the mid 30’s and wet loose avalanches will be something to monitor. If the snow is wet and slushy avoid steep terrain where loose wet snow has the potential to gain momentum and entrain deeper into the snowpack.

*Isolated snow and rain showers are in the forecast for today, but should the sun find its way through the clouds, be on the look out for wet loose activity in the mid to upper elevations. I know… this seems a little premature, but since the surface snow is light and dry, it doesn’t take much solar exposure to affect new snow. 

Weather
Mon, February 15th, 2016

Yesterday temperatures cooled to 32F at Turnagain Pass and light snowfall was observed during the day. Visibility was mostly obscured with a few periods of broken skies.   Winds were light from the Northeast and ridgetop winds averaged in the low teens (mph.)

Overnight temps remained just below freezing and no new precipitation was recorded. In Girdwood light rain stopped around midnight and winds remained light from the Northeast.

Today scattered rain and snow showers are expected. Temperatures could rise into the mid 30’s F with light rain to 1500.’ Winds will be light from the Northeast and sky cover could clear off enough to see patches of sun by late afternoon.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 31   trace   0.1    101
Summit Lake (1400′) 33   0   0   30  
Alyeska Mid (1700′) 32   3   0.39   87  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 25   ENE   11   49  
Seattle Ridge (2400′) 27   ~   ~   ~  
Observations
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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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