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Mon, December 21st, 2015 - 7:00AM
Tue, December 22nd, 2015 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

A MODERATE avalanche danger exists in the backcountry surrounding the Turnagain Pass region. Today is the second day after a 15-25+ inch storm and although signs are pointing to a stabilizing snowpack, we are still within the window for possible human triggered slab avalanches. These are most likely to be found on windloaded slopes at, or above, treeline (see below for a slab triggered yesterday). Slabs may vary in thickness from 1-3+ feet and could break above you. Always watch your partners closely and expose only one person at a time in avalanche terrain.

*There is little information about the periphery zones such as the upper elevations of Girdwood Valley, Portage Valley and Summit Lake on the Kenai. Danger in these areas could be higher than Turnagain Pass itself.

Special Announcements

Thanks to all those who participated in our first Avalanche Rescue Workshop at Turnagain Pass yesterday! The next Rescue Workshop will be on January 9th so mark your calendars.

Participants practice ‘strategic shoveling’.

Mon, December 21st, 2015
Above 2,500'
2 - Moderate
Avalanche risk
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. 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
  • 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

Yesterday was the first clear day after a quick hitting storm dropped over 2′ of snow on the North side of Turnagain Pass, lesser amounts were seen in Girdwood Valley and the South side of the Pass. Many folks were out enjoying the new snow and easing onto steeper slopes and into avalanche terrain. Despite the number of people out and about, we only had a report of one human triggered slab avalanche. This slide was triggered by a snowmachiner on the front side of Seattle Ridge (Easterly aspect ~2,200′, photos below). This slope is not especially steep, but it is on the North side of the Pass and in an area that typically sees larger snowfall amounts. More on the report HERE. Check out additional reports sent into us from Eddies, Tincan and Sunburst HERE.

If you are headed out today, remember we are still close enough to the storm that lingering wind slabs may remain sensitive to human triggers. Watch for areas with stiffer snow over softer snow and hollow feeling snow. Also look for patterns of wind loading on leeward and cross loaded slopes (35 degrees and steeper).

*Don’t forget your safe travel practices, especially considering there are very few ‘obvious signs of instability’ currently. As a reminder these signs are: recent avalanches, shooting cracks, whumphing and rapid changes in weather. Safe travel practices include: Watching your partners, having an escape route planned, grouping up in safe zones and carrying (and knowing how to use) your rescue gear in the event a person is buried.

The cooler temperatures are helping stabilize the slab avalanche potential by loosening the snow surface, but this will also contribute to larger loose snow avalanches (sluffs). Hence, keep an eye on your sluff.

 Photos above are of a snowmachine triggered slab avalanche triggered yesterday. Rider was able to throttle out. (Thanks to Chad Winberg for sending in these photos).

Additional Concern
  • Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Cornices have grown a fair bit from Saturday’s storm. As we enter a several day stretch of mostly clear weather and folks are traveling further into the backcountry, don’t forget to give these features a wide berth! 

The photo below illustrates the cornice that forms at the head of Zero Bowl (Mama’s Bowl) on the backside of Seattle Ridge. This cornice, like many others, can grow larger than many greyhound buses lined up end to end. Notice the snowmachine tracks traveling along the ridge just shy of the cornice. It can often be hard to determine how far a cornice extends when approaching from the wind ward side.


Mon, December 21st, 2015

Mostly sunny skies with valley fog covered the region yesterday. Winds have been light from a generally Westerly direction for the past 24-hours and temperatures continue to decrease  under the clear skies.

Today, we should have mostly clear skies as we are sitting between storm systems. Cooler air continues to stream in from the West and there is a slight inversion this morning; temperatures are in the 5-10F range at the road elevation and ~15F on the ridgetops. Winds are expected to remain light and variable today.

For tomorrow, Tuesday, mostly clear skies are on tap with winds turning to the West. The winds should stay light but may pick up to the 10-15mph range. It looks as though we are in this cold and clear spell to around Christmas day.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 18   0    0 58  
Summit Lake (1400′) 10   0    0 18  
Alyeska Mid (1700′) 21   0     0   38  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 18    W 4   11  
Seattle Ridge (2400′) 19    N/A  N/A    N/A  
Recent Observations for Turnagain Pass
Date Region Location
11/16/23 Turnagain Observation: Tincan Common
11/14/23 Turnagain Observation: Sunburst/Magnum
11/14/23 Turnagain Observation: Seattle Ridge
11/13/23 Turnagain Avalanche: Tincan Trees
11/12/23 Turnagain Observation: Sunburst
11/12/23 Turnagain Avalanche: Goldpan – avalanche
11/11/23 Turnagain Observation: Tincan Common
11/11/23 Turnagain Observation: Taylor Pass – Sunburst
11/10/23 Turnagain Observation: Tincan
11/10/23 Turnagain Observation: Tincan Trees
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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.