Thu, January 16, 2014 Turnagain Pass Avalanche Forecast

Thu, January 16th, 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

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

Our primary concern remains in the higher elevation zones, but poor visibility makes travel in those areas difficult. Stormy weather has been ongoing for several days now, and is expected to continue for several more. Storm snow and wind combined with warm temperatures are increasing the avalanche potential across the region.

Yesterday we were somewhat surprised to find softer conditions below treeline where wind has not been affecting the surface. Above treeline is getting raked clean by the wind, resulting in challenging snow conditions. Fresh snow is filling in slowly from the last few days.

With 5-10 inches of snow in the last 24 hours, we expect an elevated and steady danger rating to continue today. Wind slabs should be expected above treeline. The East wind through the pass will be loading West facing slopes and cross loading North and South terrain features.

Avalanche Problem 2

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 continue to find unstable test results in the old November and early December snow. These layers are no longer easy to trigger, but given the right set of circumstances it could result in large avalanches.

Check our observations page for an extensive list of photos and tests on these weak layers.

Don’t expect to experience collapsing or see shooting cracks on the deep layers any more. These problems are more likely to be quiet and unobtrusive until they awaken in a big way. With both storm layer avalanche problems and persistent slab problems, steep terrain should be avoided until the current storm cycle passes and the snowpack has at least a day to adjust.

Weather

Thu, January 16th, 2014

The last 24 hours have brought light to moderate snowfall. Weather stations have recorded 0.5 inches (Turnagain Pass) to 1.1 (Alyeska) inches of water equivalent. That adds up to 5-10 inches of snowfall. Wind has also been strong, sweeping ridgelines clean of new snow. Sunburst station had most of the recent wind from the East. Temperatures are staying in the low 30s, with a rain line creeping up to about 1000 feet.

Today looks like more of the same weather. We can expect light to moderate snowfall to continue. Accumulations may be up to 6 inches. Temperatures will hold steady.

The big pulse of moisture in the forecast is expected to happen Friday. Precipitation and wind are both forecasted to increase substantially, starting Friday morning.

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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