Sat, January 17, 2015 Turnagain Pass Avalanche Forecast

Sat, January 17th, 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

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

Yesterday my partner and I watched upper elevation starting zones being actively loaded by moderate winds out of the East. These slabs will mostly be in the 1 foot range today with areas holding deeper pockets up to 3’. Reactivity of these slabs will be on the decline throughout the day. If you find yourself venturing into high elevation starting zones approach with caution. It will take slope angles greater than 35 degrees to get slabs to release. Watch for shooting cracks and check under the surface to see how well the new snow is bonding.

Avalanche Problem 2

Glide Avalanches

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

More info at Avalanche.org

Glide cracks have been opening up over the past 2 weeks around the forecast area on all aspects. Most of the activity is in the mid elevations, around 2,500’. We were able to see some newer cracks yesterday that had formed during this past week. Glide avalanches are unpredictable and require avoidance, as they can release at anytime. Glide avalanches don’t behave the same as new snow instabilities like wind slabs. Simply knowing where glide cracks exist is half the battle. Check the observations page for more info.

Photo: Glide crack that opened up sometime in the past week on Tincan, below Common Bowl.

Tincan glide

Weather

Sat, January 17th, 2015

Temperatures over the past 24 hours have cooled with freezing levels hovering around the 1,000-1,500′ level this morning. Showery precipitation brought 1 € of new snow above 1,500′ and rain below. Winds have slowed down overnight with ridgetop stations reporting speeds in the 5-10 mph range this morning out of the East.

Today expect cloudy skies with light precipitation. Snow accumulation will be minimal with 1-2 € expected. Rain/snow line will be around the 1,000′-1,500′ level. Winds will be in the 5-10 mph range out of the East/Southeast. Temps at 1,000 will climb into the mid 30s before cooling back down again overnight.

The general pattern will remain unsettled through the long weekend. Expect rain and snow showers, light winds and temperatures to remain mild.

*Seattle wind data is 6 am-12am due to station malfunction.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	32	1	.1	30
Summit Lake (1400′)	32	0	0	5
Alyeska Mid (1700′)	33	.3	.2	18

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	26	E	16	47
Seattle Ridge (2400′)	27	VAR*	14*	33*

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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