Sat, March 16, 2013 Turnagain Pass Avalanche Forecast

Sat, March 16th, 2013

Alpine

Above 2,500'

1 - Low

Treeline

1,000'-2,500'

1 - Low

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

Small pockets of wind slab were found occasionally yesterday from the 4-5 inches of new snow that fell on Thursday. Loose snow sluff in the non-wind affected snow was also common, but less of an issue if you use good sluff management technique. Wind slab is most likely found at higher elevations, below ridgetops, and in steep terrain. Both the slabs and the sluffs are shallow and low volume, so as avalanches by themselves they are not a huge concern. The bigger concern is related to the consequences of the terrain such as cliffs or no-fall zones.

Cornices remain a low probability but high consequence avalanche problem. These large overhanging features have the potential to produce the largest avalanches today. Choose your lines to avoid cornice exposure, and always give them a wide berth when traveling on ridge crests.

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

It’s mid March already. The sun has some significant power that has already built a series of crusts on south facing slopes. As the temperatures rise this afternoon, wet loose snow may start to move at lower elevations on south exposures. Cold temperatures this morning may delay the wet cycle, and any cloud cover will also prevent the surface snow from warming.

Weather

Sat, March 16th, 2013

Yesterday was one of those perfect Alaska days. Today looks like more of the same. Temperatures are cold this morning, reaching negative temperatures in a few places. Most areas are comfortably in the teens. As soon as the sun hits we can expect rising temperatures for the rest of the day. Partly cloudy skies are forecasted. Wind should be almost non-existent.

We can expect a similar weather pattern for the rest of the week with no major storms on the horizon.

Wendy will issue the next advisory on Sunday, March 17th.

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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