Mon, January 12, 2015 Turnagain Pass Avalanche Forecast

Mon, January 12th, 2015

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

2 - Moderate

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

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

Over the last 4 days we’ve seen unusually warm temperatures above freezing at lower elevations, which has caused a lot of water to flow through the snowpack. Yesterday morning several glide avalanches were observed on the Eastern face of Seattle Ridge and the Southern face of Eddies, all below 2700′. Today rain is expected throughout the day increasing the potential for more glide activity.

Glide avalanches are common to Alaska’s maritime snowpack and occur in steep terrain where the bed surface underneath is slick. These rather unpredictable avalanches are not associated with a human trigger. They seem to happen spontaneously during prolonged periods of warming when water has lubricated the ground; as observed by a Level 2 avalanche student yesterday in a snowpit on Seattle Ridge.

In general it is best to not travel underneath or in terrain where glide cracks have formed. Fortunately they seem to be more common in steep extreme terrain and are easy to identify, thus making them avoidable.

At higher elevations there are fewer glide cracks visible, but it is still wise to plan your travel around them.

Two recent glide avalanches on the Eastern Face of Seattle Ridge were observed yesterday morning. Starting zone elevation is estimated between 2500′ – 2700′

Recent glide avalanches on Eddies South Face, elevation estimated at about 2500′.

Avalanche Problem 2

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

Today rain combined with above freezing temperatures is increasing the likelihood of wet loose avalanches at elevations below 2000’. Over the last 4 days a lot of water has drained through the snowpack causing the snow to become unconsolidated and wet at treeline. Rain today and into tonight could increase the likelihood of small human triggered wet loose avalanches on steep terrain features.

At higher elevations where temperatures have been cooler a solid melt/freeze crust has formed making this problem unlikely above 2000’. Be aware of an area between 2000’ and 2500’ where breakable crust with moist snow below could be extra challenging to ski/ride through today.

As of yesterday a very supportable melt/free crust has formed above 2500′. Notice the re-frozen rain runnels and old ski tracks on Tincan.

Weather

Mon, January 12th, 2015

After an initial rain event on Jan. 8^th this warm spring-like weather seems to be sticking around into this week. Over the last few days temperatures have been in the low to mid the 30’sF with a 3-day stretch of temps averaging 35F at Center Ridge (1880′) weather station. No new precipitation has been recorded since Jan.8^th.

Yesterday temperatures were mild, in the high 20’sF at ridgetops and mid 30’sF at 1000′. Skies were patchy with isolated areas of light precipitation, but no accumulation in Turnagain Pass was recorded. Winds were light in the morning and East ridgetop winds picked up to 10-25mph throughout the day.

Today another low-pressure system continues to bring unusually warm January weather. We expect to see rain starting this afternoon, up to .21 inches at Turnagain Pass. Rain/snow line will be around 3500′. East winds should increase to 25-45mph at ridgetops.

Tonight precipitation is expected to increase with up to 1 inch of water and rain/snow line is expected to remain around 3500′. East winds will continue to be 25-45mph at ridgetops.

There is some talk later in the week of cooler air from the artic combined with moisture helping us keep our hopes up that snow may be in our future.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	35	0	0	29
Summit Lake (1400′)	33	0	0	5
Alyeska Mid (1700′)	35	0	0	22

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	28	E	13	34
Seattle Ridge (2400′)	30	ENE	14	27

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
04/21/24	Turnagain	Observation: Bertha Creek	Anonymous
04/20/24	Turnagain	Avalanche: Spokane Creek	Schauer/ Mailly Forecaster
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

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