Thu, December 13, 2012 Turnagain Pass Avalanche Forecast

Thu, December 13th, 2012

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Moderate (2)

Below Treeline
Below 1,000'

Moderate (2)

Alpine Above 2,500'		Considerable (3)
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

The modest weight of yesterday’s snow in Turnagain pass (.5” water) probably isn’t enough to affect last Saturdays wind slab on its own. Add a skier to the equation and you will likely be able to trigger wind slabs on terrain steeper than 35 degrees. We experienced substantial whumphing at tree line yesterday where the snowpack structure begins to change (weak and unconsolidated below tree line changing to a denser slab or wind scoured above). This whumphing is a big auditory red flag that if the slope were steep enough (greater than 35 degrees) to slide, it probably would have. Below tree line we found very little to no wind affected snow.

Avalanche Problem 2

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

Yesterday’s storm snow appeared to be bonding fairly well to last Saturday’s accumulation. Snowpit test results below tree line consistently failed at the interface between Saturday’s storm snow and the November facets. Though a slab is beginning to amalgamate at these lower elevations, my greater concern today is sluffing. Our snowpack is still very loose in wind protected areas and a skier on steep terrain has the potential to entrain a significant amount of sluff in the form of storm snow and facets. Just how weak this lower elevation snow is becomes quite obvious as your ski tips continually submarine into the October and November facet layers.

Weather

Thu, December 13th, 2012

Yesterday’s storm roared through south central with a vengence leaving upwards of 15″ in favored areas such as Hatcher pass. Unfortunately Turnagain pass found itself in the “Donut hole” with a meager 4-6″ of accumulation. Overnight winds have picked up from the west and will continue to blow today in the 20-40mph range, tapering this evening. We can expect a trace amount of snow to fall today over the advisory area as temps look to stay below the freezing mark at all elevations.

This evening winds will back to the east in advance of a low pressure system building in the gulf. As this low moves into Prince William Sound tomorrow, the Chugach and Kenai mountains should experience some snowfall Friday, though highest accumulations will likely be east of our area in the Sound.

Storm totals for 12/12/12:

Turnagain pass: 4-6″

Summit Lake: 8″

Anchorage bowl: 5-11″

Girdwood: 8-12″

Hatcher pass: 12-15″

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Wendy will issue the next advisory Friday morning, December 14th.

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.