Mon, January 27, 2014 Turnagain Pass Avalanche Forecast

Mon, January 27th, 2014

Alpine

Above 2,500'

4 - High

Treeline

1,000'-2,500'

4 - High

Below Treeline

Below 1,000'

4 - High

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

The snowpack continued to degrade yesterday under a tenth consecutive day of unseasonably warm temperatures. Wet slab and wet loose avalanches remain the primary concern as temperatures stay well above freezing again today.

We have continued to see large natural avalanches in the Turnagain and Girdwood regions nearly everyday since the warm up began. Yesterday was no exception as terrain on Pete’s South proved susceptible to the rain and warm temps. The mercury continued to climb overnight and we are seeing our highest temperatures in well over 3 months this morning.

Temperatures @ 5AM in degrees Fahrenheit

Penguin Peak (4200’): 41

Sunburst (3880’): 45

Alyeska top of Quad (2800’): 50

Seattle Ridge (2400’): 47

Center Ridge (1880’): 52

Cold temperatures (well below 32F) and time are the only two factors that will bring us out of this period of elevated danger. With unseasonably warm air and moderate amounts of rain again today, the snowpack will continue to lose strength and whither away from the valley floor moving up in elevation. Travel in avalanche terrain again today is not recommended.

Yesterday I saw people kayaking Six-mile Creek, road biking, ROCK-climbing and kite surfing along the Seward Highway. Until winter returns to south-central Alaska, activities such as these are going to be the better (and probably more fun) alternative to recreating in the backcountry this June-uary.

Avalanche Problem 2

Deep Persistent Slabs

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.

More info at Avalanche.org

In the upper elevations of our zone where precipitation has been falling primarily as snow, we have a deep slab (6’+) resting on what we know is a weak foundation. Evidence of this deep slab problem presented itself on Saturday in the Girdwood Valley as pictured below. Any avalanches initiated in upper elevations today will likely be triggered either by wind or a falling cornice.

Natural deep slab avalanche on Goat Mt. SE to SW facing with ~6,000′ starting zone. Saturday Jan. 25th.

Additional Concern

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

Winds have been moderate to strong over the last 2 weeks, primarily out of the east and southeast creating some large and unruly cornices on upper elevation west aspects. Cornices are quite unpredictable and have a tendency to release during warming events.

Weather

Mon, January 27th, 2014

Scattered rain showers returned to our region yesterday with temperatures cooling slightly from Saturday night/ Sunday morning. The slight cooling was followed by rapid warming that began yesterday afternoon and continued into this morning (see Sunburst graph above) where all ridgetop stations are reporting temperatures greater than 40 degrees. Winds have continued to blow predominantly from the east in the 30-50mph range.

With the passage of this current warm front today we can expect temperatures to drop slightly throughout the day to the mid to low 40’s at 1000′. This slight cooling will not be nearly enough to shore up our snowpack, though it may drop our snowline down to around 2500′. Precip amounts will be light today with our first chance of SNOW coming later tonight in the 1-3″ range above 1000′. Ridgetop winds will continue in the 50-60mph range from the east.

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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