Mon, February 24, 2014 Turnagain Pass Avalanche Forecast

Mon, February 24th, 2014

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Moderate (2)

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

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

Wind Slabs

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

More info at Avalanche.org

Strong and gusty winds created very sensitive wind slabs during the day yesterday (see video & observation HERE). An ample amount of light density snow was moved easily by these winds and formed slabs 2-3 feet thick. We received one report of a snowmachine triggered avalanche in one of these wind loaded areas yesterday. details HERE. Natural and human triggered avalanche activity was observed and reported by multiple parties over the weekend.

Snowmachine triggered avalanche in a wind loaded starting zone in Triangle Bowl. No one was injured or buried. (Photo: Kolin Smith)

Triangle Bowl

Today expect the sensitivity of these slabs to be on the decline. It will still be possible to trigger slabs in many areas, as the winds affected slopes above and below treeline yesterday. It’s important to learn how to recognize wind slabs. Gullies that have been cross loaded, cornices and wind lips at the top of slopes, and any snow that has a smooth, rounded or pillowy look to it are worth avoiding today.

Avalanche Problem 2

Persistent Slabs

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

More info at Avalanche.org

Weak faceted snow that is sitting between the late January crust and the snow that has fallen in February continues to hold the potential for deeper slabs to release. This layer has been slowly gaining strength but still warrants your attention. Combine this problem in areas where newly formed wind slabs are up to 3 feet on their own and the consequences (volume and depth of debris) are potentially unsurvivable.

Choosing lower angled terrain, <35 degrees, is the simplest way to avoid triggering slabs up to 3’ in depth. Avoiding spots where slab depth quickly changes from thin to thick (i.e. starting zones, cross loaded gullies) will also help in avoiding trouble today.

Weather

Mon, February 24th, 2014

The most significant weather factor contributing to instability over the last 24 hours was wind. Wind data from ridgetop stations were the following:
Sunburst– 13 avg – 55 gust out of the East
Seattle– 22 avg – 53 gust out of the South
Fresno– 18 avg – 40 gust out of the North

Temperatures over the last 24 hours averaged 17 degrees F at the Sunburst weather station. It has been 6 days since the last precipitation has fallen.

Today expect sunny skies. Winds speeds will remain elevated, averaging in the 20-30mph range out of the Southeast. Temperatures at 1,000′ will be in the high 20s to low 30s F

A ridge of high pressure over most of Alaska is preventing moisture from reaching our area. There is a slight chance for some light precipitation tomorrow, but much of that depends on the ability of that high pressure ridge to prevent low pressure from the south and west to move over us. The rest of the week looks to be dry and clear with slightly warming temperatures as high pressure will continue to dominate.

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 Thu, June 01st, 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	Closed May 15.
Placer River	Closed	Closed May 15.
Skookum Drainage	Closed	Will close to motorized use on April 1, 2023 per the National Forest Plan.
Turnagain Pass	Closed	Will close on June 1.
Twentymile	Closed	Scheduled closure May 1.
Seward District
Carter Lake	Closed	Scheduled closure May 1.
Lost Lake Trail	Closed	Scheduled closure May 1.
Primrose Trail	Closed	Scheduled closure May 1.
Resurrection Pass Trail	Closed	Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor	Closed	Extended opening until May 15.
South Fork Snow River Corridor	Closed	Scheduled closure May 1.
Summit Lake	Closed	Scheduled closure May 1.