Turnagain Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Tue, December 15th, 2015 - 7:00AM
Wed, December 16th, 2015 - 7:00AM
Graham Predeger
Avalanche risk The Bottom Line

With 6-12+ inches of snow falling on Sunday night/ Monday morning from sea level to ridgetops there is a MODERATE avalanche danger in all elevation bands today.   Storm snow instabilities and loose snow avalanches are the primary concern today and are most likely to be encountered in very steep terrain.

Ice climbers: Snowfall totals in Portage Valley have been verified at 12 € or more yesterday.   This is potentially more than a €œmoderate € avalanche problem for this user group given the extreme and complex nature of the terrain.    

Special Announcements

Fireside Chat #3 €“ Human factors and decision-making on Thursday, Dec 17th!!  Join our newest CNFAIC forecaster, Aleph Johnston-Bloom Thursday night from  6:30-8:00pm in Girdwood at the Glacier Ranger Station (Forest Service office)  for an introduction to what avalanche professionals and psychologists refer to as the €œhuman factor € as it relates to decision-making in the backcountry.

More areas are open for over snow vehicles on the Seward Ranger District today!  Please see updated table at the bottom of this page.

Tue, December 15th, 2015
Above 2,500'
2 - Moderate
Avalanche risk
2 - Moderate
Avalanche risk
Below Treeline
Below 1,000'
2 - Moderate
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
  • 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

Observations from yesterday are pointing toward an overall snowpack that continues to adjust to this latest pulse of snow.  The weak snow above the Thanksgiving rain crust continues to show signs that it is gaining strength and didn’t prove to be a concern in our snowpits yesterday.  Keep in mind this set up though (see secondary concern below) and recognize that areas where wind loading has occurred, there will be more weight on this weak snow/ storm snow interface.  Large triggers such as a snowmachine could prove enough to tickle out a fresh storm slab or wind slab 2-3’ deep.

Skiers pushing into steeper, upper elevation terrain (above 3500’) may also find fresh wind slabs in the 2-3’ range as we had a short but strong wind event on Sunday night.  In areas protected from the wind and lower elevations, the surface is quite unconsolidated.  Generally with more snow on the northern end of Turnagain pass, loose snow sluffs will prove to be fast moving and high volume today, particularly in steep terrain (greater than 40 degrees).

CNFAIC forecasters are elated to be able to utilize snowmachines again as a forecasting tool after last winters “snow drought” at trailhead locations.  Here, Graham Predeger digs in to look at our current snowpack structure at 2400′ above 2nd Bowl (Jr’s bowl) on the backside of Seattle ridge. 

Avalanche Problem 2
  • Persistent Slabs
    Persistent Slabs
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.
More info at Avalanche.org

We will continue to track the Thanksgiving rain crust/ facet combo (and buried surface hoar layer) until it is buried more than 3 feet deep AND proves dormant.  Though not reactive recently, all the ingredients are present to bake that cake (2’+ storm slab/ weak snow/ stout bed surface).  For the moment, look at this avalanche problem as an additional reminder to maintain safe travel protocols, and ensure you and everyone in your crew is carrying proper rescue equipment and knows how to use it.

Tue, December 15th, 2015

Low-level fog persisted most of yesterday near sea level with broken clouds and partly sunny skies above about 500′.   The snowfall shut off early yesterday morning with no new precipitation added during the daylight hours.   Winds were calm (single digits) throughout the day and temps were in the 20’s from valley bottom to ridgetops.  

Today, temperatures are starting out slightly inverted, promoting valley fog, though with a weak pulse of moisture arriving mid to late morning, that should usher in easterly winds in the 25-40mph range at ridgetops and act to mix the air a bit.   We may see 1-3 € of snow falling from sea level and up, around the eastern Turnagain arm region with temperatures in the 20’s F at ridgetops and low to mid 30’s F at sea level.

More active weather is on tap through the workweek as another low pressure moves into the Gulf and begins to affect Kodiak as early as tomorrow.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 24   0   0   39  
Summit Lake (1400′) 23   0   0    14
Alyeska Mid (1700′)  25  0 0    33

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 19   W    4 28  
Seattle Ridge (2400′) 20    N/A  N/A  N/A
Recent Observations for Turnagain Pass
Date Region Location
11/16/23 Turnagain Observation: Tincan Common
11/14/23 Turnagain Observation: Sunburst/Magnum
11/14/23 Turnagain Observation: Seattle Ridge
11/13/23 Turnagain Avalanche: Tincan Trees
11/12/23 Turnagain Observation: Sunburst
11/12/23 Turnagain Avalanche: Goldpan – avalanche
11/11/23 Turnagain Observation: Tincan Common
11/11/23 Turnagain Observation: Taylor Pass – Sunburst
11/10/23 Turnagain Observation: Tincan
11/10/23 Turnagain Observation: Tincan Trees
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.