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Sat, January 19th, 2019 - 7:00AM
Sun, January 20th, 2019 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger is  MODERATE  above 2500′ for slab avalanches 1-2′ thick. Triggering a small slab in isolated terrain or a larger slab that could bury a person is possible on steep slopes. Cornices grew last week and could be triggered by the weight of a person or snowmachine. Identify glide cracks and avoid/limit your exposure time under this unpredictable hazard.

SUMMIT LAKE / JOHNSON PASS:  Keep in mind buried weak layers exist in the middle and base of the snowpack. More potential for triggering a large slab avalanche exists in this zone, especially in terrain that has seen recent wind-loading.  

Special Announcements
  • *Early Bird Special*   tickets are only $25 for the 5th annual SNOWBALL until midnight January 25!! Get them now, this show has always sold out! Snowball is our fun way of saying thank you and celebrating another great season together.


  • For the Hatcher Pass Avalanche Center Saturday Advisory click  HERE  and recent observations click  HERE.
Sat, January 19th, 2019
Above 2,500'
2 - Moderate
Avalanche risk
1 - Low
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
  • Persistent Slabs
    Persistent Slabs
  • Certain
    Very Likely
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Likelihood of Avalanches
Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches
Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word Size (D scale) Simple Descriptor
Small 1 Unlikely to bury a person
Large 2 Can bury a person
Very Large 3 Can destroy a house
Historic 4 & 5 Can destroy part or all of a village
More info at Avalanche.org

Although sunny and quiet weather conditions have been over the area for 2 days, there is still the possibility of triggering a lingering slab. Winds, along with several inches of snow, on Wednesday formed slabs that are sitting on weak facets and possibly even buried surface hoar in places. This is the problem, that slabs could be taking more time to stabilize due to the persistent grain type that lies under them. Slab thickness is variable – from 3″ to a foot in general with wind loaded zones that could harbor a section of 2′ slab. Keeping close tabs on the top of the snowpack is key.

Quick hand and/or pole tests to determine stiffer snow over weaker snow as well as watching for cracking around you are ways to asses a slab over a weak layer. Keep in mind smaller and harder slabs could be lurking in steep rocky terrain as well as larger and more connected slabs in bigger terrain. Be suspect of wind-loaded features and as always, evaluate the terrain for consequences and use safe travel protocols.


South of Turnagain – Johnson Pass/Summit Lake zone: A very poor snowpack structure exists in these areas.  Multiple mid-pack weak layers of facets and buried surface hoar have been found as well as a facet/crust combination in the bottom of the snowpack. No recent avalanche activity has been observed since the New Year’s storm, but more uncertainty exists for triggering a deeper more dangerous avalanche. If you’re headed this way, it will be important to evaluate terrain and snowpack as you travel. Be on the lookout for signs of instability and maintain extra caution around wind-loaded slopes. 

Surface conditions between 2,500 and 3,000′ on Magnum’s West face. Small roller balls are old, from Wednesday’s warm and windy weather. (photo: Trip Kinney)

Additional Concern
  • 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 are still slowly opening. Although we have not heard/seen one of these release for over a week now, limiting exposure under them remains wise. Known areas with cracks are Eddies, Tincan, Sunburst, Magnum, Cornbiscuit, Lipps, Seattle Ridge, Johnson Pass, Lynx Creek, Summit Lake, Petersen Creek, and Girdwood. This avalanche hazard is unpredictable and cracks can release without warning. 

Glide cracks on the SW aspect on Magnum, photographed Thursday Jan 17 by Peter Smith.

Sat, January 19th, 2019

Yesterday:   Clear skies with dense valley fog in places were seen over the region. Temperatures were inverted with teens in valley bottoms and mid-20’sF along ridgetops during the day. Winds were light and variable along ridgelines. Overnight, winds shifted to a more NW direction bringing in cooler air aloft.

Today:   Another clear sky day is on tap.  Ridgetop winds are expected to remain light from the NW.  The inversion is breaking down with the arrival of cooler air from the NW. Temperatures sit in the teens F at all elevations this morning where they are forecast to remain for the day. The exception is Summit Lake, where temperature have dropped into the single digits.  

Tomorrow:    The last day for this clear sky period is expected tomorrow. Temperatures will continue to decrease and single digits are expected. Clouds, warming temps and a chance for snow move in on Monday, while a higher chance for snowfall is forecast for Tuesday into Wednesday.  

 *Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 23   0   0   51  
Summit Lake (1400′) 9   0   0   20  
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′) 23   Variable   3   9  
Seattle Ridge (2400′) 27   *N/A   *N/A     *N/A    
Recent Observations for Turnagain Pass
Date Region Location
05/13/24 Turnagain Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South
05/13/24 Turnagain Observation: Turnagain Pass non-motorized side
05/12/24 Turnagain Observation: Warm up Bowl
05/07/24 Turnagain Observation: Turnagain Pass Wet Slabs
04/29/24 Turnagain Avalanche: Turnagain aerial obs
04/27/24 Turnagain Observation: Johnson Pass
04/23/24 Turnagain Observation: Turnagain Sunny Side
04/21/24 Turnagain Observation: Bertha Creek
04/20/24 Turnagain Avalanche: Spokane Creek
04/16/24 Turnagain Observation: Cornbiscuit
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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.