Thu, January 28, 2016 Turnagain Pass Avalanche Forecast

Thu, January 28th, 2016

Alpine

Above 2,500'

4 - High

Treeline

1,000'-2,500'

3 - Considerable

Below Treeline

Below 1,000'

2 - Moderate

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

Storm Slabs

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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’s stormy conditions caused a variety of avalanche activity at multiple elevations. Several D2’s were seen on Tincan and fresh wet debris was observed in many common slide paths along Turnagain Arm and Portage. In the last 24-hours Turnagain Pass and Girdwood have received over 2’ of new snow in the Alpine, over 2″ of rain below 2000′ combined with strong NE winds. Today an additional 6-12” of snow is expected in the upper elevations and rain below 2000′.

Expect wind slabs to be large and to have high consequences. Triggering a wind slab 2-5’ thick is likely on steep slopes today where top-loading and cross-loading will be a factor on a variety of aspects. A windslab from above could easily entrain wet snow at the mid elevation band and be quite destructive and impossible to escape. Natural activity is possible today, but with winds backing off this morning, the likelihood of natural activity will be decreasing.

Avoid putting yourself at the bottom of a big runout zone and stay off of steep terrain. Should visibility allow for travel into the alpine, keep your slope angles low and minimize your exposure to steep slopes and terrain traps. Shooting cracks may not be present until its too late.

D2 Avalanche on Tincan “CFR” WSW aspect, observerd yesterday around 3pm. This was likely a natural avalanche due to strong winds and increasing temperatures mid day.

D2 natural avalanche on the NW shoulder of Tincan, ~2600, as seen from the Seward Hwy yesterday afternoon.

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

Over 2 inches of rain has saturated the snowpack below 2000’. This hazard will be especially dangerous on steep open slopes where an avalanche from above could easily entrain a large amount of wet snow. Today it will be important to avoid steep runout zones, gully features and steep rollovers. Should you get yourself (snowmachiner or skier) stuck at the bottom of a terrain trap, escaping a wet loose avalanche from above will be impossible.

Additional Concern

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

Glides continue be in the back of our minds today, especially with the addition of a large amount of rain and snow over the last 24 hours. Several glides have avalanched over the last few days and don’t be surprised if a few more go today. Since glide cracks can spontaneously release at any time, they are best to avoid. Poor visibility today will make it harder to see existing glides, but this is one more reason to steer clear of steep slopes.

Weather

Thu, January 28th, 2016

From 6am yesterday to 7am today Turnagain Pass received a 2.2 € of water, which equals over 2′ of new snow in the Alpine elevation band. Temperatures spiked mid day causing rain to fall as high as 2500′, possibly higher for a few hours. Winds were strong from the NE averaging in the 30-40’s mph most the day with gusts in the 60’s mph.

Today another .5-1 € of water is expected to fall, adding another 6-12 € of snow in the Alpine. Temperatures will spike again mid day causing rain/snow line to reach as high as 2000′. Winds are expected to decline, 10-20mph from the NE.

Showery conditions will persist tomorrow with our first chance of sun and cooler temperatures this weekend.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	32.5	15	2.2	107
Summit Lake (1400′)	34	1	0.3	28
Alyeska Mid (1700′)	34	1	2.09	70

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	27	ENE	34	64
Seattle Ridge (2400′)	28	~	~	~

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
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
04/29/24	Turnagain	Avalanche: Turnagain aerial obs	Tully Hamer
04/27/24	Turnagain	Observation: Johnson Pass	Noah Mery
04/23/24	Turnagain	Observation: Turnagain Sunny Side	Travis SMITH
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

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