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Sun, January 2nd, 2022 - 7:00AM
Mon, January 3rd, 2022 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger remains MODERATE on all aspects above 1,000′. Triggering a wind slab avalanche, up to a foot thick, will be possible on slopes that saw wind loading yesterday or may see active loading today. Small shallow sluffs will also be possible to trigger on steep slopes. Even a small wind slab or sluff could run further than expected due a crust that sits underneath.

The danger is LOW below 1,000′ where triggering an avalanche is unlikely.

SUMMIT LAKE / LOST LAKE:  Strong NW winds impacted the Summit Lake area yesterday and may again today. Watch for wind slabs on leeward slopes. These also are likely to be sitting on a crust.

Special Announcements
  • Forecaster Chat – January 11th: Mark your calendar! John Sykes with be interviewing avalanche scientist Pascal Haegeli from Canada. Topic: How do backcountry users interpret and apply the avalanche forecast. Details HERE.
Sun, January 2nd, 2022
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. 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
  • Certain
    Very Likely
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
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.

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

The ground blizzards in Girdwood were pretty ominous for what the mountains would be like during the northerly wind event yesterday. Sure enough, there was plenty of snow pluming off the the Western Chugach range, along Turnagain Arm (gap winds), along the western Kenai Mountains, Summit Lake, Seward, etc. Despite all this, Turnagain Pass itself looks to have escaped the majority of the damage. Although there was still plenty of wind to move some snow in Turnagain, especially on the Seattle Ridge side, we had no reports of avalanches and did not see evidence of any wind slabs that released from the ridgelines that can be seen from the road.

A big part of this is that there is just not much snow available for transport. Only 3-5″ of snow from Friday that is sitting on a crust to ridgetops. One report from Seattle Ridge yesterday described the snow surface as a mix of ‘polished up crust and wind drifts’. However, the non-motorized side of the Pass appears to be in a bit better shape. The NW winds have died off, but not completely. The forecast is for 10-20mph so some continued wind effect is possible today.

If you are headed out in search of some sheltered ‘dust on crust’ conditions, it should be fairly easy to suss out where the winds have been blowing and where slabs could be lurking. Watch for changes in surface texture, the most obvious being a wind pillow, drift, or larger wind loaded area intermixed with scoured crusts. Also look for cracking in the snow around you. Winds made it into the trees, so keep an eye out for slabs in these areas as well. Slabs should be fairly small in general unless getting into the bigger terrain where they could be up to a foot thick. On steeper sustained slopes, keep in mind even a small wind slab could run fast and far as debris will be sliding on a crust.


Cracking in a shallow wind slab near treeline on the front (road) side of Seattle Ridge near the up-track. Photo by Troy Tempel, 1.1.22.


Wind transport along the southern end of Seattle Ridge yesterday due to the channeled NW winds aloft. Photo Troy Temple, 1.1.22.


Wind plumes on the easterly facing slopes of Summit Peak, just south of the Turnagain forecast zone. 1.1.22.


Loose snow avalanches (sluffs):  Shallow sluffs could be easily triggered on the steeper slopes. As with the wind slabs, debris may run faster and further than expected due to the crust.

Additional Concern
  • Deep Persistent Slabs
    Deep Persistent Slabs
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
More info at Avalanche.org

We are continuing to monitor those old November facets that sit under a dense slab of snow anywhere from 2-5′ thick; thicker on the north end of Turnagain and shallower on the south end. At elevations between ~1,200′ to ~3,000′ the facets sit on top of the Halloween crust. With the top of the snowpack now frozen from last week’s warm weather, changing the character of the slab and making it even more difficult for a person to impact this faceted layer, triggering a large slab avalanche is now very unlikely.

This problem is becoming what we call ‘dormant’ until there is a major change in the weather/snowpack to reactivate it again. This could be a big storm cycle, or the spring melt season.

Sun, January 2nd, 2022

Yesterday:  Partly cloudy skies, light to strong NW winds, and cold temperatures were over the region. The NW outflow winds averaged 5-15mph at Turnagain Pass, but as high as 30mph to the north, west and south of Turnagain. Temperatures dropped to the single digits is most locations.

Today:  Partly cloudy skies are forecast again today with the NW winds in the 5-10mph (some areas seeing up to 20mph). Temperatures are still falling and are -10 to 0F along ridgelines and the 0 to +10 in valley bottoms.

Tomorrow:  Mostly sunny skies, light variable winds and cold temperatures are expected for Monday and most of next week.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 6 0 0 67
Summit Lake (1400′) 5 0 0 24
Alyeska Mid (1700′) 5 0 0 40

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) -5 W 5 19
Seattle Ridge (2400′) -3 N 6 17
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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.