Sun, April 06, 2014 Turnagain Pass Avalanche Forecast

Sun, April 6th, 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

Yesterday marked the first real change in weather since mid-March. For the past 48-hours cloud cover and warmer temperatures have been baking the snow surface – both day and night. There were a handful of natural wet loose avalanches reported in steep North facing terrain in the Girdwood Valley yesterday. Some of these were reported to have been large enough to injure or bury a person. With last night’s slightly warmer temperatures leading into another warm cloudy (and drizzly) day today, expect to see similar wet activity.

The most likely aspects for wet slides will be terrain with a Northerly tilt. These slopes which had 2-8″ of dry faceted snow just a couple days ago are now becoming damp to wet and losing stability. These aspects have not undergone a melt/freeze cycle like the Southerlies and therefore should sluff easily for the next day or two, or until skies clear or the temperature cools. Below 1,500′ the snowpack is downright soggy and unsupportable on all aspects. Watch for wet loose avalanches on steep lower elevation slopes.

Though it looks like tomorrow or tomorrow night will be our best chance for a decent shot of snow (maybe…), below is a clip on how the snow surface and snowpack are holding up.

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

The warming we have seen during the past two days has far surpassed that of the last 3 weeks. This is a prime de-stabilizing factor for cornices which are still looming, very unpredictable and dangerous. Continued avoidance will be especially good both from above and below.

Weather

Sun, April 6th, 2014

During the past 24-hours we have seen overcast skies and temperatures in the 35-45F range below treeline and ~25-30F at the ridge tops. Light rain has been falling below 1,000′ with light snow above – only a trace of snow has accumulated. Ridge top winds have averaged ~10mph with gusts to 20mph from the East.

Today should be another overcast day with light precipitation. We may see 2-3″ in ‘favorable locations’ above treeline (Portage Valley for instance) but for the Pass it looks to be just another dusting. The rain/snow line is expected to creep up to 1,500′ as temperatures will climb to the mid 40’sF at sea level and up to 30F on the ridgelines. Ridge top winds will be from an Easterly direction around 10mph with higher gusts.

It looks like sometime Monday or Monday night colder air will drop down from the North and combine with the large scale trough that is over us now to support a chance for increased precipitation (several inches of snow). Stay tuned.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
04/15/24	Turnagain	Observation: Taylor Pass	John Sykes Forecaster
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
04/10/24	Turnagain	Avalanche: Cornbiscuit	Tyler Grundstrom
04/07/24	Turnagain	Observation: Seattle Creek Headwall	Troy Tempel

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