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ARCHIVED - Forecasts expire after 24 hours.
Issued
Wed, January 14th, 2015 - 7:00AM
Expires
Thu, January 15th, 2015 - 7:00AM
Forecaster
Heather Thamm
Avalanche risk The Bottom Line

Today the avalanche danger is MODERATE for all elevations above 1000′. Natural glide avalanches and human triggered wet loose avalanches are possible on steep slopes below 3500′. Avoid being on large steep slopes where a wet loose avalanche has the potential to pick up enough volume to be dangerous. Identify slopes with recent glide activity and avoid travel in these areas. Wind slabs 1-2′ are also worth noting on leeward slopes above 4000′.  

Wed, January 14th, 2015
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
0 - No Rating
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Dangerous avalanche conditions. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • 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

“The phrase rinse and repeat is being uttered to describe this very persistent pattern” as stated in the Southcentral NOAA forecast discussion yesterday. Rain will remain the theme for today, but that shouldn’t be an excuse. Keep those chins up, winter does exist at higher elevations. Put on your best Gortex, bring an extra pair of gloves, and throw some dry clothes in the car. You might even get lucky – yesterday a short break in the weather made for some fun wet pow turns above 2500’ and corn skiing down low.

View of Center Ridge and North side of Sunburst taken from Tincan on Jan.13, 2015. Average depth at 2500′ was 3.5′.

 

Glide Avalanches

Glide avalanches remain the primary concern in steep terrain below 3000’. Over the last three days many glide avalanches have released on the Eastern face of Seattle Ridge, and others have been observed on Eddies and Cornbiscuit. Glide avalanches occur when the snowpack as a unit slowly moves over the bed surface below. Water lubricating the slick bed surface can speed up this process, but glides are also known to release when temperatures are cooler. A glide often begins with a large crack in the snow, but it is possible for a glide to release without a crack preceding it – especially on features where the terrain does not support it from below. Be cautious, avoid slopes with any recent glide activity, and don’t put yourself under an open crack. 

New snow covering a recent glide observed on the Southwest side of Cornbiscuit, mid elevation. Photo by Tim Glassett  

  

Avalanche Problem 2
  • 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

Over the last two days 3-6” of wet snow fell on a firm crust between 2500’ to 3500’. Today another .86 inches of rain is expected with rain/snow line around 3000’ making human triggered wet loose avalanches possible on steep terrain. Wet loose avalanches usually take a little force to get them moving, but quickly pick up volume as they move downhill.  This will be a hazard on large sustained steep slopes between 2500’ – 3500’. Keep an eye out for recent snowballing, an obvious sign of wet saturated new snow. (See photo below)

At lower elevations rain has been draining through the snowpack making the snow wet and poorly bonded. Below 2500’ human triggered wet loose avalanches are possible. Again avoid sustained steep slopes or terrain traps, like a steep drainage. 

*Below 2000′ it is our recommendation to stick to areas that have been compacted by other skiers, like the up-track at Tincan, where snow conditions are more supportable and favorable for sking/riding.

 

Wet snowballs rolling down the Southwest aspect of Pete’s North as observed from the road on Jan.13, 2015 

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

At elevations above 4000’ snow accumulation of up to 1-2’ is possible. Sustained Eastern winds 20-40mph will continue throughout the day along with more snow at this elevation band. Human triggered wind slabs of up to 2’ thick will be possible today on leeward slopes above 4000’.  

Weather
Wed, January 14th, 2015

Above freezing temperatures, high winds and rain have been the theme over the past week and this persistent weather pattern will continue into the coming days.  

Over the last 24 hours heavy rain became light in the morning and Turnagain Pass only received 0.2 inches of water compared to Girdwood at 0.85 inches. Winds were mostly East 20-25mph with ridgetop temps around 30F. Rain/snow line was between 2500′ and 3000′.  

Today temps will remain warm with rain/snow line around 3000′. Strong East winds will continue (25-40mph) and rain will increase in intensity early this afternoon with 0.86 inches of water expected throughout the day.

More rain is likely overnight, 1.38 inches is forecasted to fall at higher elevations in Girdwood and Turnagain Pass. Winds will remain strong into the evening and rain/snow line may drop slightly to 2500′.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 37   0   .2   29  
Summit Lake (1400′) 38   0   .15   5  
Alyeska Mid (1700′) 36   0   .85   21

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 29   E   25 54  
Seattle Ridge (2400′) 31 ENE   20   49  
Observations
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.