Mon, January 21, 2013 Turnagain Pass Avalanche Forecast

Mon, January 21st, 2013

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

Recent snow in the higher elevations have fallen on slick and hard surfaces. While the snowfall amounts have been modest, the winds overnight have been transporting this snow onto leeward aspects, mainly West to North facing slopes. With temperatures forecasted to increase throughout the day, expect these slabs to become more sensitive to human triggers. Expect to see shallow pockets of windslab at mid elevations (up to 1800′) in open areas to be the most sensitive today, as these slabs have fallen on a firm crust and will heat up more readily than slabs in the higher elevations today. On the flip side, these slabs are not as large (<6″) as slabs in the upper elevations (>12″). Avoiding steep upper elevation starting zones which have a pillowy or wind affected look will also be important, as these slabs, once released, have the potential to carry people downslope and into terrain traps today.

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

It is important to not forget the poor structure of the base of our snowpack. Snowpit tests over the past week continue to show weak faceted snow persisting near the ground. The large dense slabs that formed over the holidays are now able to support a lot of weight. The chances of initiating one of these slabs is getting more difficult by the day. If you were to trigger one of these deep slabs, the outcome would be bad, as the volume of snow could be very large. We are clearly in a dormant period for this avalanche problem, as it has been a week now since any new deep slab activity has been reported. Unfortunately, the weak snow is being well preserved in many areas and will continue to lurk well below the surface for the forseeable future. Staying away from areas showing exposed rocks, ground or vegetation will be important in avoiding this problem today, as these are the most likely areas to trigger a deep slab avalanche.

Weather

Mon, January 21st, 2013

In the past 24 hours Turnagain Pass has received ~6″ of new snow with .3-.5″ water equivalent. Winds have been moderate out of the E and SE averaging 20 mph with gusts to 36 mph. Temps, which have been on a steady rise overnight have averaged near 32 F at 1800′, and in the mid 20s F at 3800′.
Expect clouds to be on the increase through the day, winds out of the East 20-35 mph and a chance of precipitation with up to 3″ of new snow possible in the mountains. Temperatures will climb into the mid 30s F at 1000′.
The extended outlook calls for a greater chance of snow tonight, with precip continuing into the middle of this week.

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Wendy will issue the next advisory, tomorrow morning January 22nd.

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.