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ARCHIVED - Forecasts expire after 24 hours.
Issued
Wed, January 27th, 2016 - 7:00AM
Expires
Thu, January 28th, 2016 - 7:00AM
Forecaster
Aleph Johnston-Bloom
Avalanche risk The Bottom Line

As rain, wind and snow impact the Turnagain Pass and surrounding areas today we will have a  CONSIDERABLE  avalanche danger at all elevations above 1,000′. Human triggered storm and wind slab avalanches will be likely on slopes 35 degrees and steeper. Natural avalanches will be possible. Cautious route finding and conservative decision-making are advised as the storm continues through the day.

Yesterday was an active day for glide avalanches. Avoid traveling in areas where glide cracks threaten from above.  

The avalanche danger is MODERATE below 1000′ where debris running into channelized terrain from above is possible.

Special Announcements

There have been ten people killed in avalanches in the United States since January 16. Fatalities have occurred in Colorado, Utah, Wyoming, Montana, Washington, and Alaska.  This in the largest number of US avalanche fatalities in January since at least 2001.  Click  here  to read an analysis of this by Spencer Logan, an avalanche specialist at the Colorado Avalanche Information Center.  More information and preliminary reports on all of these acidents can be found at  Avalanche.org.  

Have you filed for the PFD? Remember you can still PICK.CLICK.GIVE  for  The Friends of the CNFAIC.Your donations are greatly appreciated and an integral part to making the CNFAIC possible and sustainable.

Wed, January 27th, 2016
Alpine
Above 2,500'
3 - Considerable
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
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. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. 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
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

After a brief break in the stormy weather yesterday, that gave backcountry travelers an opportunity to get out in the sunshine, we are back in it today with a warm, wet and windy storm rolling through. Overnight there has been .5 of water, roughly 5-8″ of snow. Today we are expecting another .5″-1″ of precipitation; this equates to rain below approximately 1,500′ and 5-10″ of snow above. The winds have been blowing 30-40 mph from the ENE with gusts up into the 70s actively loading leeward terrain.

In the Alpine, above 2,500′, where dry snow is falling avalanche issues are expected to be confined to what we call ‘storm snow instabilities’. This means avalanches will be composed of the new storm snow and are not expected to break into layers deeper in the pack. The question will be how well the new snow bonds to the old snow. The most likely avalanches will be on wind loaded slopes where fresh wind slabs 5-20″ thick have formed. These are always the most ‘touchy’ during formation or just after. Avoid travel on or under steep leeward terrain. Smooth rounded surfaces, hollow feeling snow, stiff snow over soft snow and shooting cracks intiated traveling on foot or machine, are all signs of wind loading and something to steer clear of on steep slopes today. 

In the 1000′-2500′ elevation band pay attention rain on snow and to how well the new snow is bonding to the old rain crust/snow surface, expect wind slabs especially in cross loaded areas like Seattle Ridge. The rain/wet snow combination may create the conditions for wet loose avalanches in this elevation band. 

*Cornice falls will again be a concern today with the warm temperatures, new snow and wind loading. These can break naturally at anytime as well as under the weight of a person. They can trigger an avalanche below and be very dangerous. 

Note: The Girdwood Valley recieved about twice as much water (.9″) as Turnagain pass Sunday and additional load last night. If venturing into the upper elevations around Girdwood, fresh wind slabs and storm slabs are likely to be thicker.  

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

Several recent glide avalanches were observed yesterday. Glide cracks are continuing to open and grow. These are dangerous and unpredictable. As with cornices, these are best dealt with through avoidance and limiting any exposure underneath them. Poor visibility today will make it harder to locate the exisiting glide cracks in the terrain.

 

 

 

Glide avalanche on Seattle Ridge. We believe this released in the early morning yesterday.

 

Weather
Wed, January 27th, 2016

Yesterday, cloudy skies in the morning gave way to mostly clear and sunny weather in the afternoon. Temperatures were in the mid-20Fs above 3000′ and low 30Fs around 1000′. Winds from the ENE were in the teens throughout most of the day and then picked up to 30-40 mph range overnight. Gusts reached into the 70s this morning. .5″ of precipitation (5” of snow above 1500′)  fell overnight.

Today skies will be cloudy with a mixture of snow and rain as the storm continues. Precipitation is forecasted to be heavy at times. Up to an 1″ of water (5-10″ of snow) is possible. Temperatures will be in the high 20Fs to mid 30Fs. North to  East winds, 25 to 30 mph decreasing in the afternoon. Additional rain/snow showers are expected overnight.  

This stormy pattern continues through the week as a low in the Gulf and associated strong frontal system effect the region.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 30    3 .5   92  
Summit Lake (1400′)  29  0 0   29
Alyeska Mid (1700′)  33  2.5 .25   73

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  23  ENE  25 74  
Seattle Ridge (2400′)  26 n/a   n/a   n/a  
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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.