Fri, January 16, 2015 Turnagain Pass Avalanche Forecast

Fri, January 16th, 2015

Alpine

Above 2,500'

2 - Moderate

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

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

Rain and warm temps over the last week have weakened the snowpack up to 2,500’ in elevation. Wet loose avalanches will be easiest to trigger on slopes over 35 degrees today. This is a manageable problem, in that it is relatively easy to recognize when you are in this snowpack; your skis or board will sink well below the surface and the snow will be unsupportable. When you find yourself in this snowpack set up avoid steep terrain. This becomes more important if and when you are traveling above terrain traps, such as gullies, trees, cliff bands or creek bottoms. Getting swept into these kinds of features will amplify the consequences of being caught in a wet loose avalanche today.

Avalanche Problem 2

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

Above 3,000’ mostly snow has fallen of late. Slabs generally around 1 foot in depth with deeper pockets (up to 2 feet) could be triggered on steep leeward slopes today. Assessing how well the new snow is bonding can be done with quick hand pits and will help in understanding the potential for a wind slab to release. Performing stability tests will give you more information in helping to anticipate the potential for triggering. These slabs will be somewhat difficult to trigger but have the potential to entrain additional snow once moving downhill, especially closer to the line where wet loose avalanches are a concern.

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

Glide avalanche activity seemed to take a break yesterday. Glides have been observed on many slopes around Turnagain Pass and are worth steering clear of. This is not a manageable problem, as glide avalanche release is very difficult to anticipate and the volume of these slabs is high enough to injure and bury a person. Avoidance of terrain showing glide cracks is recommended for the foreseeable future.

Weather

Fri, January 16th, 2015

Temperatures have remained mild over the past 24 hours with freezing levels remaining around the 2,000′ mark. The rain/snow line has fluctuated between 2,500′ and 2,000′, with snow accumulation in the 3-4 € range. The Turnagain Pass DOT/RWIS station reported .6 € of H20 in the past 24 hours. Ridge top winds have been moderate out of the East at 25 mph.

Today expect more of the same, as a Low centered over Bristol bay will spin and draw moisture and warm air from the South. Rain will fall at sea level. The rain/snow line will be around 1,500′-2,000′. New snow amounts will be in the 2-3 € range above 2,000′. Winds will be out of the Southeast at 20-30 mph.

The extended outlook is calling for a continuation of above average temperatures and showery conditions through the weekend. Temps will cool slightly as cold air tries to nudge its way towards the area.

* Alyeska Mid station data is from 6am – 3pm due to station being down.

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

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	34	0	.4	28
Summit Lake (1400′)	33	0	.1	5
Alyeska Mid (1700′)	36*	0*	.5*	18*

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	26	E	25	70
Seattle Ridge (2400′)	29	VAR	16	84

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
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
04/10/24	Turnagain	Observation: Cornbiscuit South Face	Todd Kelsey
04/10/24	Turnagain	Avalanche: Tincan	N. Dumont J. Carlberg

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