Thu, December 03, 2015 Turnagain Pass Avalanche Forecast

Thu, December 3rd, 2015

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

1 - Low

Below Treeline

Below 1,000'

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 aftermath of the avalanche cycle November 27th/28th is evident in the terrain on Turnagain pass. There were a number of large slides in the Alpine but much of the steep terrain did not avalanche during this last cycle. It has been almost a week since our significant loading event and there have been no recent signs of instability reported. Recent snow has provided great riding conditions and folks have been enjoying the mostly stable return to winter in the advisory area.

We continue to be suspect of steep, primarily northerly terrain that still may harbor facets that formed during the early November cold snap. Digging and probing yesterday highlighted that variability of snowpack depth and structure. Areas that are shallow and that have stiff snow over weak facets (sugar snow) are the main concern. This poor structure still has the potential to present as a Persistent Slab avalanche. This could be especially hazardous in steep, high consequence terrain where even a small slide could take you for a dangerous ride. Probing and trying to investigate the depth and layering in the terrain you are choosing to ride are recommended before committing to big lines.

We have limited information on the snowpack characteristics in the Girdwood valley and the Summit area. Both zones also have variability and warrant caution when venturing into avalanche terrain.

Remember to always practice safe travel rituals on steep slopes, namely, only expose one person at a time, watch your partners carefully, and regroup in safe zones.

Photo: D3 avalanche in Superbowl/Corner Pocket reported on November 29th. We believe this slide occurred during the November 27th/28th cycle. The remnants of the crown are highlighted in red.

Weather

Thu, December 3rd, 2015

We had mostly clear skies yesterday, light winds and temperatures the mid-20Fs as a ridge moved over the region. Today will be partly to mostly cloudy with snow showers developing as the next low effects the advisory area. Snow is expected to be light with the possibility of a brief heavier shot of snow overnight. Snow amounts forecasted are for 2-4″ today and 1-3″ tonight. Winds will be light and Easterly and temperatures will be in the 20Fs to mid-30Fs.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	26	0	0	25
Summit Lake (1400′)	21	0	0	21
Alyeska Mid (1700′)	30	0	0	18

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	23	NE	10	21
Seattle Ridge (2400′)	24	NA	NA	NA

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

Riding Areas

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