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Issued
Sat, April 16th, 2016 - 7:00AM
Expires
Sun, April 17th, 2016 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

A  CONSIDERABLE  avalanche danger remains on all slopes under 2,500′ in elevation due to an active glide avalanche cycle. Destructive glide avalanches are occurring daily across the region.  Avoid being under the runout of glide cracks.  In addition to glide avalanches, natural wet loose avalanches are possible and human triggered likely in steep terrain that harbor wet and saturated snow.

In the Alpine the avalanche danger is generally LOW.  Low doesn’t mean no however and watching for lingering wind slabs, cornice falls (give these guys a WIDE BERTH!) and human triggered wet sluffs could be seen.  

***Travel is not recommended in avalanche terrain on the West (motorized side of Turnagain Pass).

*ATTENTION HIKERS: Summer use trails crossing under avalanche terrain should be avoided due to avalanche hazard from above. Byron trail in Portage Valley and Crow Pass are two examples of trails not recommended right now.  

Special Announcements
  • We are finished publishing weekly summaries for the Summit Lake zone. Please see the final Summit Lake Summary and springtime tips  on this link. Reminder: as the season winds down, we will continue to publish all reports/observations sent in to us!

  • Tomorrow is the last day of  daily  avalanche advisories. Between Monday, April 18th and Saturday, April 30th we will be issuing advisories on weekends and Tuesday and Thursday during the week.
Sat, April 16th, 2016
Alpine
Above 2,500'
1 - Low
Avalanche risk
Treeline
1,000'-2,500'
3 - Considerable
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. 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
  • 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

Yesterday’s hampered visibility limited some information regarding new glide avalanche activity, however, we were able to get a look at Seattle Ridge and a few other areas along the Seward Highway. New avalanche activity seen yesterday:

New glide avalanches:
– Paths off of Pk 4940, across from the Granite Ck Campground (South facing, photo below)
– Penguin Ridge (South facing)
– Eddies (South facing)

*Note: no new glide releases were noted on Seattle Ridge

New wet avalanches:
– Wet loose avalanche above Bertha Creek Campground @ 3:30 yesterday
– Small wet loose slides and roller balls seen on Pete’s South, Southerly aspect

This current wet snowpack, combined with today’s weather (light rain, cloudy and possible sun), has us prepared for another round of glide activity. Our message remains the same: to avoid being under glide cracks and respective runout zones. To be in the wrong place at the wrong time when a glide releases could likely be deadly. Considering the motorized up-track is threatened by cracks, we are recommending that people do not travel on the up-track or in runout areas along Seattle Ridge. Glide avalanche hazard also exists on the non-motorized side of Turnagain Pass in certain zones, most pronounced on Southerly aspects. 

Left photo: New glide releases on South facing Pk 4940.                Right photo: Glide releases on Seattle Ridge and a melting out snowpack.

 

 

Close up view of the Seattle Ridge snowmachine up-track. Several cracks threaten the route along with remnants of a natural wet loose avalanche that occurred Thursday (4/14)

 

 

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

Yesterday temperatures rose to 32F at 2,500′ and light rain and cloud cover since has likely kept the mid-elevation surface wet and unsupportable. It was no surprise to hear of a natural wet loose avalanche witnessed on a SE facing slope above the Bertha Ck Campground. These wet loose slides will be a concern again today with our warm temperatures. Any periods of sunshine will also be a factor and increase the chances for natural activity. Natural wet loose avalanches are possible on all aspects at elevations below 2,500′ and human triggered wet loose sides are likely. In the Alpine, Human triggered wet sluffs are possible on slopes seeing warming by the sun.

*Remember wet loose avalanches can be hard to escape once initiated and particularly hazardous if they push you into a terrain trap.

Additional Concern
  • Normal Caution
    Normal Caution
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
More info at Avalanche.org

At elevations above 2,500′ and in the Alpine the snowpack is generally stable. There are a few things to watch for if skies open enough for travel to the upper elevations:

– Lingering wind slabs that could be triggered in steep rocky terrain 

– Cornice falls (we have yet to see cornices start falling in the Alpine but this could happen any day with our warm temps)

– Wet sluffs on steep solar aspects

Weather
Sat, April 16th, 2016

Yesterday’s weather consisted of mostly cloudy skies and occasional light precipitation. Past 24-hour accumulations were up to 0.2″ of rain up to 2,500′ with 1-2″ of wet snow above this. Areas on the South side of Turnagain Pass and Girdwood Valley saw only a trace. Ridgetop winds have been moderate, averaging 10-15mph with gusts to the 20’s from the East. Temperatures rose to the low 40’sF at 1,000′ yesterday (32F at 2,500′) before cooling off to the mid 30’s at 1,000′ (upper 20’s at 2,500′).

For today, partly cloudy skies and intermittent rain showers are possible (trace of snow above 2,200′) adding only 0.1″ of water. It’s possibly the sun could come out later in the day. Ridgetop winds will be ~10mph from the East while temperatures stay warm (rising to 45F at 1,000′ and 32F at 2,500′).

Sunday looks to be a short break between low-pressure systems that are churing in the Gulf. We could see sunshine along with high clouds and light winds. Another bout of moist Southerly flow looks to move in on Monday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 36   rain   0.2   111  
Summit Lake (1400′) 37   0   0   28  
Alyeska Mid (1700′) 37   0   0.03   96  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 28    NE 12   28  
Seattle Ridge (2400′) 30     SE   12   24  
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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.