Sat, January 11, 2014 Turnagain Pass Avalanche Forecast

Sat, January 11th, 2014

Alpine

Above 2,500'

3 - Considerable

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

2 - Moderate

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

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

The persistent slab is a problem that doesn’t go away quickly. The last major storm was on Sunday, almost a week ago. Since that storm, when many large avalanches were recorded, we haven’t seen a lot of avalanche activity. This is mostly due to a lack of triggers (people) in the backcountry this week. However, the problem has been bad enough to warrant an extended stretch of elevated danger ratings. Our test pits performed every day this week have not shown appreciable improvents in the strength or propagation potential of the snowpack. Check this video for a test done yesterday on Pete’s North.

It’s worth recapping some of our recent avalanche activity to pick out the trends. Avalanches have been triggering remotely, often from ridges and propagating across large distances. Wind blown ridges offer a trigger point where the snowpack is shallow and a person’s weight is more likely to collapse the buried weak layer. In deeper areas, a collapse may still be caused by a larger trigger such as a snowmachine or a group of people. Avalanches have been observed on all aspects (N, S, E, and W), and elevations from just below treeline to >3500 feet. Few people have ventured into higher elevation steep terrain, which is a good self-preservation tactic right now.

Standard warning signs such as whumphing, shooting cracks, or avalanches on small indicator slopes are unlikely right now. Avoiding steep terrain is the only effective management tool we have to deal with the current problem.

Weather

Sat, January 11th, 2014

No new snow has accumulated in the last 24 hours. The last major storm ended on Sunday. This week has been mild weather with warm temperatures, little precipitation, and light wind.

Today we can expect mostly cloudy skies, highs in the mid 20s. Mostly light wind.

The next storm system may arrive by the middle of the coming week. Stay tuned.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
10/27/24	Turnagain	Observation: Tincan	Michael Kerst
10/21/24	Turnagain	Observation: Turnagain Pass Road Observation	Trevor Clayton
10/19/24	Turnagain	Observation: Tincan – Below Todds Run	Andy Moderow
10/18/24	Turnagain	Observation: Taylor Pass	Eli Neuffer
10/15/24	Turnagain	Observation: Tincan Common	John Sykes Forecaster
10/14/24	Turnagain	Avalanche: Tincan	CNFAC Staff
05/13/24	Turnagain	Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South	H Thamm
05/13/24	Turnagain	Observation: Turnagain Pass non-motorized side	Amy Holman
05/12/24	Turnagain	Observation: Warm up Bowl	Tony Naciuk
05/07/24	Turnagain	Observation: Turnagain Pass Wet Slabs	A S

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