Turnagain Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Fri, March 30th, 2018 - 7:00AM
Sat, March 31st, 2018 - 7:00AM
Wendy Wagner
Avalanche risk The Bottom Line

The avalanche danger continues to be  MODERATE  above 1500′ in the periphery of the forecast zone, such as Girdwood Valley and South of Turnagain Pass. Triggering a hard slab avalanche 2-4 feet thick remains a possibility and may be triggered remotely. A generally  LOW  danger exists in the core zone of Turnagain Pass where triggering this type of avalanche is trending toward unlikely.  Pay attention to afternoon warming and give cornices a wide berth.  

Similar avalanche concerns exist in the  Summit Lake area  and other zones on the Kenai.

Fri, March 30th, 2018
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
  • Deep Persistent Slabs
    Deep Persistent Slabs
  • Certain
    Very Likely
  • Historic (D4-5)
    Very Large (D3)
    Large (D2)
    Small (D1)
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.

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

As the days go by with little in the way of weather to contribute to avalanche danger, the chances for triggering an avalanche are decreasing. It has been over two weeks since the last snowfall, a week since the last human triggered avalanche and the snowpack is adjusting to the weak layers that sit in the middle and base of the snowpack. Terrain in the core Turnagain Pass zone is trending towards a LOW danger, meaning triggering a slab avalanche is unlikely – but not out of the question. Areas on the periphery, such as Girdwood Valley and the South end of the Pass towards Johnson and Lynx, we are more concerned with as they have a thinner snowpack and poorer structure.

Yesterday a large collapse was triggered under Goat Mountain in the Girdwood Valley (see Heather’s video below). This is a sign the snowpack can still produce a dangerous slab avalanche. The slabs in questions are hard slabs 2-4′ thick. The weak layers in question were formed in January and are various layers of facets and buried surface hoarThough these layers are becoming harder and harder to trigger, there is still a chance someone could hit the wrong spot. This is a low probability, high consequence situation and makes travel in avalanche terrain tricky. No obvious signs of instability may be present before a slope releases and it may be the 10th skier or snowmachiner onto a slope that finds the trigger point. These trigger points are often in thinner areas of the snowpack near rocks or in scoured areas along ridges. 

If the sun shines in full force today be aware of warming later in the day on Southerly slopes. Especially steep southerly slopes with rocks that will help heat up the snow around them, aiding in possible wet avalanche activity. As we gear up for a weekend of sunny skies, keep the afternoon warming on your radar!


 Poor snowpack structure and poor pit results found in the Girdwood Valley yesterday. This video was taken in Gulch Creek under Goat Mountain near 3,000′.


A loot at Turnagain Pass from the top of the uptrack on Tuesday. It has been over two weeks since snowfall and surfaces are hard and crusty from either the sun, wind or both.


Additional Concern
  • Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Cornices are large in many places. As we head into warmer, sunnier weather remember this can help de-stabilize them. As always, give cornices plenty of space and limit exposure underneath them.

Fri, March 30th, 2018

Partly cloudy skies were over the region yesterday. A few snow flurries were seen in the morning but no snow accumulated at Turnagain Pass. A few inches were found in the upper Girdwood Valley. Ridgetop winds have been light from the North and West during the past 24 hours (5-10mph). Temperatures were in the teens yesterday along ridgetops and in the mid 30’sF in valley bottoms. Overnight, valley bottom temperatures have cooled slightly to 25-30F.  

Today, Friday, partly cloudy skies this morning should give way to mostly sunny skies this afternoon as high pressure has built in over our area. Ridgetop winds look to remain light from the North in the 5-10mph range. Temperatures are expected to stay in the teens along ridgetops and warm to the mid 30’sF again at 1,000′.  

For the weekend, we can expect high pressure to remain, which will bring mostly sunny skies and Northerly winds. Cool temperatures look to stay in place for Saturday, but warmer a air mass may push in Sunday or Monday. This could bring more spring-like conditions.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  27 0   0   76  
Summit Lake (1400′) 28   0   0   31  
Alyeska Mid (1700′) 27   0   0   72  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 17   W   6   12  
Seattle Ridge (2400′) 24   NW   8   23  
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
Riding Areas

The riding areas page has moved. Please click here & update your bookmarks.

Subscribe to Turnagain Pass
Avalanche Forecast by Email

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.