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Sat, April 30th, 2016 - 7:00AM
Sun, May 1st, 2016 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

Another round of rain/snow and wind will increase the avalanche danger to CONSIDERABLE on all aspects and elevations above 1,000′. On slopes below 2,500′, where it is raining, large glide avalanches and wet snow avalanches may release naturally. In the upper elevation terrain, where it is snowing, fresh wind slabs and loose snow avalanches are possible along with cornice falls.  

*Avoiding travel under glide cracks and cornices is recommended. These are the most dangerous avalanche problems right now.

For tomorrow, avalanche conditions will likely remain similar to today as the storm system over us does not look to exit until Monday. When the storm exits –  REMEMBER: WHEN SKIES CLEAR – DIRECT SUN WILL INCREASE THE AVALANCHE DANGER.  

*ATTENTION HIKERS:  Summer trails crossing under avalanche terrain should be avoided. Byron trail in Portage Valley and Crow Pass trail are two examples of trails with dangerous avalanche hazard above.

Special Announcements
  • Today is our LAST backcountry forecast for the Turnagain Pass and surrounding areas. We will be posting ‘springtime tips’, our Annual Report, a user survey and other end of season information on Monday, May 2nd.  

  • We will continue to publish all reports/observations sent in to us. Don’t be shy –  pass along what you see  if you are getting out in the mountains!!
Sat, April 30th, 2016
Above 2,500'
3 - Considerable
Avalanche risk
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

We close this season with the same primary avalanche concern that we have had for months….the glide avalanche. One new glide release was seen yesterday on the South face of Pete’s North ridge. There is no end in sight to these destructive slides on slopes below 3,000′ – until the snow is gone. The BIG question remains: what will happen to the Alpine? Will these upper elevations start ‘shedding’ and large avalanches occur? Or will they slowly melt out with mainly inevitable large cornices that fall? It depends on the weather. Rain has not reached the Alpine yet – if it does, we can expect this to weaken the pack promoting large wet slides. Direct sun will also weaken it, but a long stint of high pressure can season the pack and promote a slow melt out. Time will tell.

For now: Travel is NOT recommended on, or in the runout of, slopes with glide cracks or cornices above. 

Photo below: New glide avalanche from yesterday on Pete’s North. It is tough to see the crown but the snowpack here is 10-12′ thick, so the crown is equally thick. 


Photo below: Seattle Ridge up-track. Although no one is traveling here and motorized access is closed, man this is impressive carnage!! You can faintly see the old snowmachine tracks on the bottom left.

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

Intermittent rain showers below 2,000′ continue to add water to an already saturated snowpack (we are expecting 1.5-2″ of rain from now through Sunday). Despite the rotten, wet and mushy snow at these lower elevations, we have yet to see large wet sluffs gouge into deeper layers of the pack. Something to keep an eye out for.

Above 2,000′ where wet snow has been falling, shallow wet sluffs are occurring. These are mainly composed of the new snow as the photo below shows. There is 1-2′ of new snow at the high elevations from the past 3 days and another foot forecast by tomorrow, if the sun comes out, watch for wet sluffs and even slabs to release taking this thicker layer of new snow.

Photo below: Tincan Ridge and many shallow wet snow sluffs from the new 6″-ish of snow on Wednesday.

Additional Concern
  • 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

Dry and moist snow avalanches are possible at the highest elevations, above 3,500′. These are new snow instabilities and in the form of wind slabs and new snow sluffs. There is 5-7″ of snow forecast today with another 5-7″ tonight and another 5-10″ by tomorrow night. If this storm produces, wind slabs at these high elevations could be 2-3′ thick in places by Sunday.

Watch for CORNICES: These are large and falling every now and then. One piece of cornice fell on the South face of Sunburst yesterday – triggering a wet sluff below that ran to the valley bottom.

Sat, April 30th, 2016

Rain showers continued yesterday at elevations below 2,000′ while snow has been falling at higher elevations. Over the past 24-hours we have seen ~.5″ of rain and 2-6″ of heavy snow above treeline. Over the past 3 days we have seen ~1.5″ of rain with up to 10-15″ of wet snow above 2,500′. Temperatures remain warm (40’sF at 1,000′ and ~30F at 2,500′). Ridgetop winds have been averaging 20-30mph from the East.  

For this weekend another wet storm is moving in. We are expecting 1-1.5″ of rain up to 2,000′ by tomorrow morning and another .5-1″ on Sunday. Anywhere from 10-20″ of wet snow is possible at the higher elevations by Sunday night. Ridgetop winds are forecast to increase to the 30-40mph range from the East. Temperatures should remain mild, up to 40F at 1,000′ and 30F at 2,500′.

Looking into this coming week, we could see some sunshine Monday into Tuesday before continued showery weather sets back in.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 37   2   0.5   104  
Summit Lake (1400′) 38   0   0   11  
Alyeska Mid (1700′) 36   0   0.5   84  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 28   NE   25   60  
Seattle Ridge (2400′) 29   SE   20   36  
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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.