Wed, March 19, 2014 Turnagain Pass Avalanche Forecast

Wed, March 19th, 2014

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Low (1)

Below Treeline
Below 1,000'

Low (1)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Low (1)
Below Treeline Below 1,000'		Low (1)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

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

It has been 4 days since any avalanche activity has been reported. This most recent activity involved deep slab avalanches pulling out on layers buried 3-5 feet below the surface. While the likelihood of triggering this type of avalanche is waning, the consequences remain high. Slabs up to 5 feet in depth have the potential to pull out across entire slopes and do a significant amount of damage.

What’s tricky with this avalanche problem is that you will not encounter it everywhere. The slab that built up last week is now strong and able to hold a lot of weight. Because of this it is possible to get onto steep terrain without incident. Now is not the time to let your guard down. We know that some areas still harbor weak reactive snow below the March slab. (See VIDEO and OBSERVATION for a more detailed desrciption)

Areas where you would be more likely to trigger a deep slab are in rocky areas, transition zones between wind scoured and wind loaded, steep terrain, and slopes with an overall shallower snowpack. Avoiding these areas is the best way to tip toe around this problem.

Photo below: Deepest part of the crown face (8′) of the Widow Maker avalanche (March 15); a prime example of a deep slab avalanche Wendy Widow Maker Crown

Click HERE for a detailed write up of this avalanche.

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

Cornices have become sufficiently large over the course of the winter. It is difficult to predict when these monsters will release themselves. Strong solar radiation and an absence of wind are two factors that can encourage cornices to drop onto slopes. Avoiding being on or under cornices is a good habit to get into. Know where the cornice begins and the underlying terrain ends. If you are traveling below cornices, spread your group out and only expose one person at a time.

Additional Concern

Dry Loose

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.

More info at Avalanche.org

The sun will be strong today on mainly South through West facing terrain. Daytime heating will last into the evening hours, given that sunset is now after 8pm. Low volume loose snow avalanches will not be a concern on their own. In steep terrain above terrain traps it will be important to be on the lookout for wet loose avalanches, as they have the potential to knock you off your feet and into trees, gullies or over cliffs.

Weather

Wed, March 19th, 2014

In the past 24 hours no new precipitation has fallen. Temperatures at the Sunburst station (3,812′) have averaged 19 degrees F. Winds there have been light, averaging 7mph out of the Northwest with a max gust of 23.

A pleasant day in the mountains is on tap. Expect clear skies, winds out of the North at 15mph and temperatures at 1,000′ reaching into the high 30s F.

A large area of high pressure is establishing itself over most of the state. This will bring clear and dry conditions over the next several days.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/22/23	Turnagain	Avalanche: Tincan	Nick D'Alessio
05/12/23	Turnagain	Avalanche: Tincan, Sunburst, Magnum, Cornbiscuit	Heather Thamm
05/07/23	Turnagain	Observation: Tincan – Bear Tracks	CNFAIC Staff
05/05/23	Turnagain	Observation: Seattle Ridge	AS/ WW Forecaster
05/02/23	Turnagain	Observation: Cornbiscuit	Schauer/ Sturgess Forecaster
05/02/23	Turnagain	Observation: Seward Hwy Turnagain Pass	Joel Curtis
04/30/23	Turnagain	Observation: Magnum	Ayla, Kit Crosby, Barton
04/29/23	Turnagain	Observation: Tincan	John Sykes
04/28/23	Turnagain	Avalanche: Taylor Pass/Pastoral	Schauer/ Creighton Forecaster
04/28/23	Turnagain	Avalanche: Tincan	Andy Moderow

Riding Areas

Updated Sat, September 23rd, 2023

Status of riding areas across the Chugach NF is managed by the Glacier and Seward Ranger Districts, not avalanche center staff. Riding area information is posted as a public service to our users and updated based on snow depth and snow density to prevent resource damage at trailhead locations. Riding area questions contact: mailroom_r10_chugach@fs.fed.us

Area	Status	Weather & Riding Conditions
Glacier District
Johnson Pass	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Placer River	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Skookum Drainage	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Turnagain Pass	Closed	Scheduled opening on the Wednesday before Thanksgiving per Chugach National Forest plan. Subject to adequate snow cover.
Twentymile	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Seward District
Carter Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Lost Lake Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Primrose Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Resurrection Pass Trail	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Snug Harbor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
South Fork Snow River Corridor	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.
Summit Lake	Closed	Scheduled opening per Chugach National Forest plan December 1. Subject to adequate snow cover.