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ARCHIVED - Forecasts expire after 24 hours.
Issued
Sun, January 26th, 2020 - 7:00AM
Expires
Mon, January 27th, 2020 - 7:00AM
Forecaster
Ryan Van Luit
Avalanche risk The Bottom Line

Today the avalanche danger is LOW at all elevations. LOW danger does not mean NO danger. Loose snow avalanches (sluffs) remain possible to trigger, especially in steeper terrain. On steep sustained slopes, dry snow avalanches could entrain a significant amount of surface snow and run to valley bottoms. Normal caution is advised for other concerns including cornices, glide cracks and small isolated wind slabs.

PORTAGE VALLEY, SUMMIT LAKE, LOST LAKE:  Areas east and south of Turnagain Pass have seen an increase in wind over the past two days. Small to large wind slab avalanches may be possible to find and trigger and Extra Caution is advised in these outlier areas.

Sun, January 26th, 2020
Alpine
Above 2,500'
1 - Low
Avalanche risk
Treeline
1,000'-2,500'
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. 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
  • Dry Loose
    Dry Loose
  • Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
    Size
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

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 loose surface snow has remained under mostly clear and cold skies since it fell on Monday.  Today calls for more cold temperatures, calm winds and partly cloudy skies, so it’s unlikely the snow conditions will be an exception to the recent trend and loose snow sluffs remain a concern.  Monday’s snow has had time to settle, but due to temperatures averaging around 0°F and nominal to calm winds, it hasn’t formed slab character.

Loose dry or “sluff” avalanches are predictable.  We know in most places the surface is covered with loose snow, and as the slope angle increases, the ease to trigger sluff avalanches increase.  Once this sluff is initiated it could quickly gain both volume and momentum.  If you’re venturing into steep terrain, consider making a plan to manage your sluff  – it could easily knock you off your feet and take you with it down the fall line.  Remain mindful when in areas with rocky outcrops and cliffs.  Because it’s our primary concern, consider reading through this article on sluff management.

Yesterday, observers watched riders trigger and effectively manage loose dry sluff avalanches in the steeper sections of Sunburst. 1.25.20  Photo: CNFAIC Archive

Wind Slab avalanches:  The northwest outflow winds have been moving down Cook Inlet and for the most part, have spared the Turnagain Pass area. Because it’s prudent to stay sharp, feel for stiffer snow over softer snow and look for smooth pillowed drifts. This issue is mainly outside of our forecast zone, but as wind can do sudden and unexpected things, we need to be on the lookout for wind effect in any area we travel.

Locations suspect for wind slabs:  Summit Lake, Johnson Pass, Bench Peak and all the way south to Seward. The Seward area saw significant wind over the past two days with some natural avalanche activity. Portage Valley and the Whittier areas. North of Girdwood in the Crow Pass region.

Cornices and Glide Cracks:  As always, limit exposure under glide cracks and give cornices a wide margin.

These riders at Cornbuscuit are limiting exposure to the glide cracks above by moving swiftly while underneath them and maintaining spacing between one another.  1.25.20 . Photo: CNFAIC Archive

 

Weather
Sun, January 26th, 2020

Yesterday:  Mostly sunny skies with light ridgetop winds, 5-10mph from the northwest.  Temperatures ranged from about -10°F to 5°F at all elevations.

Today: Partly sunny trending toward mostly cloudy this evening, with a high near 2°F. Winds will be out of the Northwest around 5 mph. There’s a chance of accumulating a trace of snow today, mainly after 9pm.

Tomorrow:  Mostly cloudy with snow likely throughout the day accumulating 1-3″. Temperatures will see a high near 10°F and a low of 3°F. Winds will be around 5 mph out of the northwest shifting to east for the evening.

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

Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) -7 0 0 44
Summit Lake (1400′) -11 0 0 17
Alyeska Mid (1700′) -3 0 0 43

RIDGETOP 24-hour data (6am – 6am)

Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) -1 W 5 12
Seattle Ridge (2400′) -7 NNE 5 11
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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.