Sat, January 25, 2014 Turnagain Pass Avalanche Forecast

Sat, January 25th, 2014

Alpine

Above 2,500'

3 - Considerable

Treeline

1,000'-2,500'

3 - Considerable

Below Treeline

Below 1,000'

3 - Considerable

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

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

One of the new big avalanches seen at Turnagain Pass was on Pete’s North. The Southwest face pulled out full depth sometime Thursday afternoon to Friday morning.

As long as we have warm temperatures, this kind of avalanche is possible. It’s worth noting that these large destructive avalanches are happening across a huge region in southcentral Alaska. Valdez is currently under seige with the Richardson highway closed (second photo below). Check out this observation for more photos and video from the Summit Lake region.

Sun exposure today may have enough power to tip the balance on south facing slopes in the afternoon.

Pete’s North

Keystone Canyon on the Richardson highway, Friday Jan 24th. From the City of Valdez Facebook page.

Avalanche Problem 2

Deep Persistent Slabs

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

More info at Avalanche.org

At the bottom of our snowpack we still have weak snow from November that is making full depth avalanches a reality. This is most obvious from 3000 feet elevation and below where rain-on-snow has created an especially difficult problem. Even higher up, above the rain line, it’s been snowing for more than a week. The snowpack at higher elevations is finally getting deep, but stability is in question until we have evidence to suggest it won’t slide. Remember, before the storm that dumped many feet of snow on these slopes we had numerous natural and remote human triggered avalanches. Now that the problem is buried deeper it may be harder to trigger but the consequences of resulting avalanches will be significantly worse.

Weather

Sat, January 25th, 2014

The hose of pacific moisture that’s been hitting us for the past week has shifted back to the west for the time being. Unseasonably warm temperatures continue today, some of the weather stations are currently at the highest we’ve seen all month. Freezing level is expected to reach 4400 feet elevation again today.

Partly sunny skies are forecasted today. Look for fog in the valleys. Southeast to East wind blowing 42-61 mph at the ridgetops.

6am temperatures

Center ridge snotel – 39 F

Sunburst – 32 F

Alyeska Max’s mt – 34 F

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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