Tue, January 26, 2016 Turnagain Pass Avalanche Forecast

Tue, January 26th, 2016

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

Below Treeline

Below 1,000'

1 - Low

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

Surface instabilities in the form of fresh wind slabs make up the primary avalanche concern today. With more wind than precipitation yesterday in the Turnagain pass area we can expect to find wind slabs in the 6-12” range on wind-loaded and cross-loaded slopes above treeline. As these last couple of storms have come in quite warm, wind slabs appear to be adhering well and may be stubborn to initiate. Very steep, wind-loaded terrain may be the exception. Overall, across the Turnagain pass zone (and above about 2K), the snowpack is deep and is lacking any reactive persistent weak layers. Aside from glide cracks (more info below) any instability today should be relegated to the top 12-18” of our snowpack. You can quickly test for surface instability by conducting hasty hand pits or jumping on (no consequence) test slopes with your skis or machine.

Cornices deserve a note as well, as these warm, windy storms prove ideal to continue to add to their mass. Avoid time spent below and when travelling along a corniced ridge, whether on skis or snowmachine maintain a healthy distance (and then some!) from the edge.

Note: The Girdwood Valley recieved about twice as much water (.9″) as Turnagain pass yesterday. If venturing into the upper elevations around Girdwood, fresh wind slabs and storm slabs are likely to be thicker.

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

Visibility yesterday limited a look at many of the glide cracks that we’ve been monitoring over the last 2-weeks, including a behemoth on the SW face of Corn Biscuit. If someone were to tangle with a glide avalanche, it would simply be a ‘wrong place at the wrong time’ scenario. It’ll be best to limit or avoid altogether time spent underneath glide cracks and recognize them for the dangerous, unpredictable avalanche problem that they are.

This photo is of a very large glide crack as observed last Thursday, 1/21. Yesterday, visibility was too poor to see if this had progressed anymore toward failure but see Wendy’s obervation from 1/24. She was able to see visible changes in this crack over an hour timespan.

Another concern today in this mid-elevation band comes in the form of wet-loose avalanches as the snowpack is quite heavy and wet below 2,000′. With continued warmer than normal temps and a slight chance of a few rays of sun today, we may see some wet-loose and/ or roller ball activity in steep, mid-elevation terrain.

Weather

Tue, January 26th, 2016

A low ceiling and steady precipitation around eastern Turnagain arm dominated yesterday’s weather. Temps were hovering around 34 F at 1,000′ (37 F at sea level) with a rain/ snow mix at the Turnagain pass parking lots and the rain-snow line around 1,300′. Ridgetop winds were moderate from the NE averaging in the 30’s and gusting to 63 mph before tapering off a bit overnight. Center ridge SNOTEL site (1880′) picked up a couple inches of snow (.4 € water) in the last 24 hours while Girdwood picked up .9″ of water as reported at the Alyeska mid-station.

Today looks to be a slight break in our active weather pattern before another Low and associated front rolls through southcentral AK tomorrow morning. Temperatures are expected to be in the mid-30’s at 1,000′ with ridgetop winds from the East in the 10-25mph range. Skies will be mostly cloudy but we shouldn’t expect to see more than an inch or two of snow wrung out today in favored areas of the Pass.

More unsettled weather is on tap as we head toward the weekend with the big quetion being precipitation type and just where that rain/ snow line will fall.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	32	2	.4	92
Summit Lake (1400′)	33	1	.2	28
Alyeska Mid (1700′)	33	0	.9	73

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	26	ENE	28	63
Seattle Ridge (2400′)	28	n/a	n/a	n/a

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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