Turnagain Pass RSS

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ARCHIVED - Forecasts expire after 24 hours.
Issued
Mon, January 25th, 2016 - 7:00AM
Expires
Tue, January 26th, 2016 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

A MODERATE avalanche danger exists today above 1,000′ in the mountains around Turnagain Pass. At elevations above 2,500′ fresh wind slab avalanches ~6-12″ thick will be possible to trigger on steep wind loaded slopes. Below 2,500′, a MODERATE danger exists for glide cracks that may release spontaneously and avalanche. More details on these in the discussion below.

**If snowfall intensifies today adding more than 6″ in the area you are recreating in, the avalanche danger will trend toward  CONSIDERABLE where natural avalanche will be possible and human triggered wind slabs could be likely.

Special Announcements

We are sad to report that as of yesterday the US has seen 9 fatalities in the past 9 days. One of these was the last fatality at Hatcher Pass (Hatcher Pass has seen 3 this season). You can view these reports at avalanche.org

  • Don’t forget about tonight – Monday, January 25th, 7-8 pm:  Come to the Blue and Gold Board Shop for a FREE Avalanche Awareness class taught by CNFAIC forecaster Heather Thamm. For more details click here:  HERE.  
Mon, January 25th, 2016
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
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
  • 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

A lot of people are wondering if the earthquake shook loose any avalanches yesterday? Well, the answer is yes, but not anything too big or bad or ugly – that we know of. With ok visibility yesterday, it looked as though several chunks of cornice fell and some of these triggered small wind slab pockets below them.

Below is a photo from South facing Magnum Ridge:

 

Check out the many observations sent in to us yesterday – many of these were from the Alaska Avalanche School’s Level 2 course – thanks!

 

Avalanche concerns for today at the higher elevations (above 2,500′ where it is snowing) will focus on the new snow and wind. We have seen another 4-6″ of snow along with strong Easterly ridgetop winds overnight; this is on top of the 6″ from Saturday night. Today we are expecting an additional 2-6″ of snow with the moderate to strong winds remaining. Yesterday, wind slabs were stabilizing rapidly due to the warm temperatures and ‘sticky’ nature of the snow. We are expecting similar conditions for today. What to look for if visibility allows for travel above treeline:

  • How the winds have drifted the new snow from overnight and what sections of the slopes are loaded
  • Watching for shooting cracks
  • Jumping on wind loaded test slopes 
  • Quick hand and pole pits to see how any new slab is shearing 
  • Feeling for stiffer snow over softer snow


If you find cracking or any signs pointing to sensitive wind slabs steer clear of that slope. These slabs are sitting on a generally stable snowpack and not expected to step down into any deeper layers in the pack.

**However, shallow zones such as the Summit Lake area and South of Turnagain Pass harbor a variety of old weak layers in the pack. These have been mostly unreactive but something to keep in mind if a new load is placed on them. See the Summit Lake Summary from Saturday for more on this.

Although cornices got a good shake early yesterday morning, give these a wide berth as they could still be prime to fall.

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

Glide cracks continue to open and widen, yet we did not see any new releases yesterday. See video below from Corn Biscuit ridge (we were almost sure this thing was going to avalanche while we were up there…). As we keep mentioning, limiting time, or avoiding time altogether, under these things is highly recommended!

 

 

Closeup of a portion of the Corn Biscuit glide crack.

Weather
Mon, January 25th, 2016

Obscured skies along with pockets of blue holes covered the area yesterday. Winds were in the moderate range on the ridgetops, 15-20mph from the East. Intermittent light snowfall (rain below 1,000′) was seen with no accumulation.

Overnight, another warm and wet front has moved over us associated with a large low-pressure in the Gulf. Precipitation started falling around 9pm and as of 6am this morning, .5″ of rain has fallen below 1,500′ with 5″ of dense snow above treeline. The Easterly ridgetop winds have jumped as well, these are blowing in the 30’s mph with gusts in the 60’s. Temperatures are in the mid 30’s at 1,000′ and the mid 20’s F at 4,000′.

Today we should see cloudy skies with continued snowfall adding 2-6″ of dense snow above 2,000′ and ~.25-.5″ of rain below 1,800′. Ridgetop winds are slated to remain in the 20-30mph range from the East with stronger gusts and temperatures will stay warm…(mid 30’s F at 1,000′ and mid 20’s F on the ridgetops). Keep in mind with this weather pattern it will be possible to see more snowfall than predicted.

Tuesday, a break between systems will bring intermittent snow showers with some possible sunny breaks. Stay tuned.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 32   3    0.5 90  
Summit Lake (1400′) 35   1    0.1 27  
Alyeska Mid (1700′) 33   2    .6 74  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 25  ENE  24 62  
Seattle Ridge (2400′) 27   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.
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