Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, January 18th, 2017 - 7:00AM
Expires
Thu, January 19th, 2017 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

There is a MODERATE  avalanche danger in the Alpine where triggering a fresh wind slab on leeward terrain is possible and in protected steep areas  loose snow avalanches could be fast moving and run further than expected.  At Treeline and below the avalanche danger is LOW  where triggering an avalanche is unlikely.  

***Placer and 20 Mile open today and there is limited information about the snowpack in these areas. Approach terrain with a cautious mindset and be  on the lookout for Red Flags like recent avalanches, shooting cracks and collapsing. Watch for active wind loading as winds increase today. Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!!

***In the Girdwood Valley where 2.5′-3′ of snow fell this weekend, twice as much as Turnagain Pass, heighten avalanche conditions exist.  Triggering a persistant slab 3+ feet thick or a larger loose snow avalanche is possible in Girdwood and should warrant extra caution!!!

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Wed, January 18th, 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

There is an uptick in the westerly wind speeds this morning and this is supposed to continue throughout the day with gusts into the 30s at ridgelines. Since the recent snow fell over the weekend observers have been finding mostly loose soft snow that has not been acting as a slab with the exception of a shallow skier triggered soft slab on Eddies west face witnessed on Monday. As wind speeds increase it is important to remember that there is a lot of soft snow available for transport. Fresh wind slabs may form throughout the day and be sensitive to triggering. Steep, unsupported, leeward slopes will be most suspect. 

Be on the lookout for wind transporting snow and pillowed or drifted areas. Avoid places where the snow feels stiffer and more affected by winds. 

Skier triggered shallow wind slab on Eddies West Face. Witnessed on Monday 1.16.17

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

Yesterday small natural loose snow avalanches and skier triggered sluffing was observed. These were larger in Girdwood where there is more loose snow. Today in areas protected from the wind triggering a loose snow avalanche will be possible on steeper slopes. Fast moving “sluff” could entrain snow, run further than expected and easily knock you off your feet. Manage this problem by letting the snow move past you and choose terrain that doesn’t have high consequences if you fall. Although it is unlikely to bury a person, keep in mind that larger terrain will have more volume. Cold temperatures could increase this problem thoughout the week as the surface snow becomes even less cohesive. 

 

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 with in the snowpack and vary across our region. With the exception of avalanche mitigation in Girdwood we have not been seeing avalanches breaking into old weak layers. If traveling in this part of the forecast area this is important to remember. Prior to the storm Girdwood had a shallow, weak (faceted) snowpack and now this is under 2-3 ‘ of snow.  Limited snowpack information for this zone exists, triggering a deeper more high consequence avalanche is still possible. Should you see recent avalanche activity, experience shooting cracks, or “whumpfing” these are obvious clues that the snowpack is unstable. 

Observers have easily been able to pick out a buried layer of surface hoar in the lower elevations below 1500’ that was buried by this last storm event. This was found to be unreactive and does not seem to pose a much of a hazard at this point but will be important to keep in mind with more snow load in the future.  

If venturing into Placer or 20 Mile today remember we have very little snowpack information about both areas. We have a variety of weak layers and if you find the right spot with enough slab overlying one triggering an avalanche is still possible. It always advised to ride slopes one at a time, have a escape route planned, watch your riding partners and avoid terrain traps like steep gullies. Ease into terrain and let us know if you see an signs of instability today. 

Weather
Wed, January 18th, 2017

Yesterday was partly cloudy, cold and winds were calm.  Temperatures were around 0F, slightly colder in the valleys and slightly warmer at ridge tops.  Overnight temps were below zero and winds picked up early this morning bumping into the teens with gusts in the 20s from the W.  

Single digits temperatures will continue today. Winds are forecasted to be NW 15-25 with gusts into the 30s. Skies should be mostly clear with some scattered clouds. Tonight and tomorrow will be similar. There is a chance of snow Friday into the weekend and temperatures are forecasted to rise as the deep polar air mass retreats.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  -4  0  0 42  
Summit Lake (1400′)  -8  0  0 15
Alyeska Mid (1700′)  4  0  0  43

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 0   W   5   15  
Seattle Ridge (2400′) -2 rimed    rimed  rimed
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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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