Sun, January 26, 2020 Turnagain Pass Avalanche Forecast

Sun, January 26th, 2020

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

Dry Loose
Certain

Very Likely

Likely

Possible

Unlikely

Likelihood
Historic (D4-5)

Very Large (D3)

Large (D2)

Small (D1)

Size

Dry Loose

Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.

Likelihood of Avalanches

Terms such as "unlikely", "likely", and "certain" are used to define the scale, with the chance of triggering or observing avalanches increasing as we move up the scale. For our purposes, "Unlikely" means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. "Certain" means that humans will be able to trigger avalanches on many slopes, and natural avalanches are expected.

Size of Avalanches

Avalanche size is defined by the largest potential avalanche, or expected range of sizes related to the problem in question. Assigned size is a qualitative estimate based on the destructive classification system and requires specialists to estimate the harm avalanches may cause to hypothetical objects located in the avalanche track (AAA 2016, CAA 2014). Under this schema, "Small" avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become "Large" enough to bury, injure, or kill people. "Very Large" avalanches may bury or destroy vehicles or houses, and "Historic" avalanches are massive events capable of altering the landscape.

Signal Word	Size (D scale)	Simple Descriptor
Small	1	Unlikely to bury a person
Large	2	Can bury a person
Very Large	3	Can destroy a house
Historic	4 & 5	Can destroy part or all of a village

More info at Avalanche.org

The loose surface snow has remained under mostly clear and cold skies since it fell on Monday. Today calls for more cold temperatures, calm winds and partly cloudy skies, so it’s unlikely the snow conditions will be an exception to the recent trend and loose snow sluffs remain a concern. Monday’s snow has had time to settle, but due to temperatures averaging around 0°F and nominal to calm winds, it hasn’t formed slab character.

Loose dry or “sluff” avalanches are predictable. We know in most places the surface is covered with loose snow, and as the slope angle increases, the ease to trigger sluff avalanches increase. Once this sluff is initiated it could quickly gain both volume and momentum. If you’re venturing into steep terrain, consider making a plan to manage your sluff – it could easily knock you off your feet and take you with it down the fall line. Remain mindful when in areas with rocky outcrops and cliffs. Because it’s our primary concern, consider reading through this article on sluff management.

Yesterday, observers watched riders trigger and effectively manage loose dry sluff avalanches in the steeper sections of Sunburst. 1.25.20 Photo: CNFAIC Archive

Wind Slab avalanches: The northwest outflow winds have been moving down Cook Inlet and for the most part, have spared the Turnagain Pass area. Because it’s prudent to stay sharp, feel for stiffer snow over softer snow and look for smooth pillowed drifts. This issue is mainly outside of our forecast zone, but as wind can do sudden and unexpected things, we need to be on the lookout for wind effect in any area we travel.

Locations suspect for wind slabs: Summit Lake, Johnson Pass, Bench Peak and all the way south to Seward. The Seward area saw significant wind over the past two days with some natural avalanche activity. Portage Valley and the Whittier areas. North of Girdwood in the Crow Pass region.

Cornices and Glide Cracks: As always, limit exposure under glide cracks and give cornices a wide margin.

These riders at Cornbuscuit are limiting exposure to the glide cracks above by moving swiftly while underneath them and maintaining spacing between one another. 1.25.20 . Photo: CNFAIC Archive

Weather

Sun, January 26th, 2020

Yesterday: Mostly sunny skies with light ridgetop winds, 5-10mph from the northwest. Temperatures ranged from about -10°F to 5°F at all elevations.

Today: Partly sunny trending toward mostly cloudy this evening, with a high near 2°F. Winds will be out of the Northwest around 5 mph. There’s a chance of accumulating a trace of snow today, mainly after 9pm.

Tomorrow: Mostly cloudy with snow likely throughout the day accumulating 1-3″. Temperatures will see a high near 10°F and a low of 3°F. Winds will be around 5 mph out of the northwest shifting to east for the evening.

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

	Temp Avg (F)	Snow Depth (in)
Center Ridge (1880′)	-7	44
Summit Lake (1400′)	-11	17
Alyeska Mid (1700′)	-3	43

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	-1	W	5	12
Seattle Ridge (2400′)	-7	NNE	5	11

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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