Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, December 10th, 2016 - 7:00AM
Expires
Sun, December 11th, 2016 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

A generally  LOW  avalanche danger exists across all elevations bands for the Turnagain Pass zone. Triggering a 1-2′ avalanche is unlikely but not impossible. The most suspect slopes are in steep terrain at the high elevations where someone just might be able to break off an old wind slab or find a slope with the buried surface hoar that hasn’t slid. Good travel habits, such as exposing one person at a time, watching your partners and grouping up in safe zones are, as always, key ways to minimize risk.  Ease onto steep slopes and be mindful of people below you and on adjacent slopes.

There is snow to sea level and amounts have been adding up enough to put a LOW danger rating on the Below Treeline Elevation band. Portage Valley received 6-8″ of snow yesterday. This should be part of the equation if you are heading to ice climb this weekend, a small slide could have high consequences.

*If venturing into the ‘periphery’ forecast zones, such as Girdwood Valley or out of the core Turnagain Pass terrain, more caution is advised due to limited information about the snowpack in these areas.  

If headed to Summit Lake check out the Saturday Summit Lake Summary  HERE.    

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Sat, December 10th, 2016
Alpine
Above 2,500'
Low (1)
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
Low (1)
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
  • Normal Caution
    Normal Caution
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
More info at Avalanche.org

It has been a week since we had any report of human triggered avalanche activity and observers are not reporting signs of instability. As a mostly calm, clear and cold weather pattern dominates our area and continues into next week, we are in the “normal caution” phase of avalanche issues. These include:

1- Triggering an outlier avalanche. This would most likely be an ‘unsupported slab’ that sits above a cliff or steep rocky terrain. More specifics below in the concerns.

2- Triggering a cornice fall. The cornices maybe be small right now, but they are large enough to take you down somewhere you don’t want to go. As always, give them a wide berth.

3- Sluffs on steep slopes. These have yet to have been observed as a problem but as the surface becomes weaker under clear skies the potential will increase. 

Remember LOW hazard doesn’t mean NO hazard! It is still important to look for signs of instability and use good travel techniques. 

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

Even with LOW avalanche danger it is still important to remember the weak layer 1-2′ below the surface i.e. the notorious Nov 16th buried surface hoar. Although we have not seen an avalanche release in this layer since last Saturday and the slab character has been changing due to the cold temperatures, there are many slopes away from the ‘popular’ zones that have yet to be tested. These are the areas most suspect over the weekend. Finding the spot that harbors this weak layer, still has a slab and hasn’t been skied or slid already still could be dangerous… Triggering is unlikely but not impossible! 

 

 Buried surface hoar in a pit on Sunburst, December 6th. SW, 3200′

Additional Concern
  • 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

Several wind events over the last two weeks have formed wind slabs near and below ridgetops on a variety of aspects.  Old stiff supportable wind slabs in thin rocky areas may pop once you are out onto the slab. Be wary of hard over soft snow, hollow sounds and steep slopes with obvious deposition in the start zone.

Weather
Sat, December 10th, 2016

Yesterday was mostly clear above the valley fog, which crept higher as the day progressed. Temperatures were in the low 20Fs and decreased through day. Winds were light and variable. Overnight temperatures dropped into single digits in the valleys and were in the teens up high. The wind speeds bumped into the teens gusting into the high 20s from the east.

Today will be cold and clear with light easterly winds shifting to north in the afternoon. Tonight and tomorrow look very similar with temperatures getting colder through the weekend. Single digits to mid teens should be expected. This weather pattern dominates into next week. Look for a potential shift with warmer temperatures and a chance of precipitation later in the coming week.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  19 0    0 21  
Summit Lake (1400′)  13  0  0    4
Alyeska Mid (1700′)  22  0  0  11

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  18 variable    7 27  
Seattle Ridge (2400′)  21 variable    6  25
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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