Turnagain Pass RSS

ARCHIVED - Forecasts expire after 24 hours.
Sat, February 28th, 2015 - 7:00AM
Sun, March 1st, 2015 - 7:00AM
John Fitzgerald
Avalanche risk The Bottom Line

The avalanche danger is MODERATE in the Alpine today.   2′ slabs could be triggered in steep terrain.     These slabs have the potential to propagate across slopes and be large enough to carry, injure or bury a person.  

The danger is LOW at Treeline, where a crust caps the surface and avalanches are unlikely.

Sat, February 28th, 2015
Above 2,500'
2 - Moderate
Avalanche risk
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
0 - No Rating
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
  • 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

A long dry spell back in late January created a layer of weak faceted snow that has now been buried by several storms.  These storms produced several slabs that now average 2 feet in thickness in the Alpine.  The combination of slab over weak layer can be found consistently above 2,500’.  The two areas that are most unstable are:

Steep terrain between 2,500-3,000’.  The slab/weak layer combo is sitting on a firm crust in this elevation band.  The slab is thinner in this lower half of the Alpine, making it easier to impact the weak layer.  Parties continue to report collapsing in this elevation band and test results point to continued unstable snow in this zone.

Steep terrain with a Southerly component.  A stout sun crust formed over 10 days ago in this terrain and has slabs in the 1 foot range sitting on it.  We have seen sporadic natural activity in this type of terrain recently and mainly on the periphery of the forecast area.

While it has been 7 days since the last loading event, the nature of a persistent weak layer is that is can remain active for a long time.  If you’re considering getting into committing terrain keep in mind that you may find the most unstable snow well below starting zones.  Because of this it will be important to pick lower angle terrain (35 degrees or less) and slopes that provide escape options along the way.

Avalanche Problem 2
  • 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

A few inches of new snow will fall by the evening hours in the higher elevations.  Very shallow slabs in the 6” range will form and be sensitive to human triggers in steep (40 degrees and over) terrain.  This is not a significant hazard but is worth keeping in mind if you are travelling above terrain traps such as cliffs, gullies, or trees.

Sat, February 28th, 2015

The past 24 hours brought mild temperatures and increasing cloudiness to the area.   Winds were light out of the East and no new precipitation fell.

Today expect cloudy skies with light snow in the afternoon.   Snow accumulation will be light, in the 1-2 € range.   Temperatures will be mild with ridgetops climbing into the high 20s F and a rain/snow line around 1,000′.   Ridgetop winds will be out of the East at 5-10 mph.

The thin band of moisture that will deliver a quick shot of snow will be replaced by high pressure by Sunday morning.   A large low pressure system will move across the Bering Sea and connect with a low in the North Pacific in the early part of next week, bringing the next chance for precipitation on Tues night.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 33 0 0 40
Summit Lake (1400′) 29 0 0 6
Alyeska Mid (1700′) 27 0 0 23

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 30 E 7 26
Seattle Ridge (2400′) 31 NW 13 28
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.