Thu, April 17, 2014 Turnagain Pass Avalanche Forecast

Thu, April 17th, 2014

Alpine

Above 2,500'

2 - Moderate

Treeline

1,000'-2,500'

2 - Moderate

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

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

Thinning cloud cover combined with a drop in temps overnight have allowed the surface to refreeze at all elevations. That firm surface will lose strength as the day progresses, with temperatures at 1,000’ expected to reach into the high 40s F. Travel will become difficult as rising temperatures and sunshine will allow snowmachines and skis/boards to sink well below the surface. It will be important to get off of steep sunlit terrain (over 40 degrees) in the higher elevations and all terrain in the lower elevations as the melting occurs. Wet loose sluffs will be easy to initiate as things heat up. These avalanches will have the potential to knock you over and cause injury. It will be equally important to plan your route back to your vehicle with this heating in mind; anticipate the terrain you will need to move through and plan accordingly.

Avalanche Problem 2

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

Temperatures will rise considerably today. This will aid in destabilzing cornices that have grown over the course of the entire winter. Steer clear of cornices. When travelling at or above their level, know where they connect to the underlying terrain. When travelling below make sure that you are out of the potential fall line of these massive blocks of snow.

Weather

Thu, April 17th, 2014

In the past 24 hours no measurable precipitation has fallen on Turnagain Pass. Clouds were consistent during the day yesterday and have gradually dissipated overnight. Ridgetop temperatures have averaged in the high 20s F (27 F at Sunburst station). Winds there have been light averaging 9mph (max gust 25 mph) out of the East.

Today expect clearing skies and continued mild temps. Temperatures at 1,000′ will reach into the high 40s F and ridgetops should see temps into the low 30s F. Winds will remain light out of the East at 5mph. Only an occasional rain/snow shower can be expected for today.

The extended outlook is showing another day of mild and partly cloudy weather, with light rain showers possible on Friday. A quick break on Saturday will bring sunny skies before another weak low pressure brings back clouds and light rain on Sunday.

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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