Thu, December 05, 2013 Turnagain Pass Avalanche Forecast

Thu, December 5th, 2013

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

1 - Low

0 - No Rating

1 - Low

2 - Moderate

3 - Considerable

4 - High

5 - Extreme


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

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.

More info at Avalanche.org

If I had to pick one of our avalanche problems to talk about a primary concern, then wind slab would be the one. We have not seen any pockets with a tendency to pop under the weight of a person. Even in the places where stiff surface snow can be found, it has a stubborn, low tension nature.

In areas that are not exposed to wind, the snowpack is 15-30 inches of weak faceted snow. The cold and clear temperatures combined with shallow snow have formed a steep temperature gradient and changed the snow to big sugary crystals.

The snowpack is shallow… Exposed rocks and vegetation are abundant. That lack of coverage is probably the biggest safety concern for skiers and snowboarders in the backcountry right now.

Weather

Thu, December 5th, 2013

It has been nearly a week since significant snowfall. Cold temperatures and clear skies gave way to a big change yesterday, but not the white stuff that we were hoping for. Temperatures at some ridgetop weather stations are above freezing this morning. A freezing rain advisory is in effect for Anchorage and the greater region, including Girdwood and the Kenai peninsula. Driving conditions deteriorated yesterday evening with a slick glaze of ice on the roads, and that freezing rain will continue today.

Freezing rain is expected to form a surface crust on our snowpack. This isn’t an avalanche concern for now, but may become a weak layer interface when the crust gets buried by later snow storms.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
04/16/24	Turnagain	Observation: Cornbiscuit	Krueger / Matthys Forecaster
04/15/24	Turnagain	Observation: Taylor Pass	John Sykes Forecaster
04/15/24	Turnagain	Observation: Seward Highway – Tern Lake to Portage	Joel Curtis
04/14/24	Turnagain	Observation: Sunburst	T. Olsen-Lund, R. Sullivan I. Adams
04/14/24	Turnagain	Observation: Turnagain Pass Snomo	K. Gallaher
04/13/24	Turnagain	Observation: Spokane Creek	Everet Megli
04/11/24	Turnagain	Observation: Tincan	John Sykes Forecaster
04/10/24	Turnagain	Avalanche: Seattle Ridge	Schauer/ Keeler Forecaster
04/10/24	Turnagain	Observation: Cornbiscuit South Face	Todd Kelsey
04/10/24	Turnagain	Avalanche: Tincan	N. Dumont J. Carlberg

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