Tue, February 26, 2013 Turnagain Pass Avalanche Forecast

Tue, February 26th, 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

Storm Slabs

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

Even light snowfall adds up over time and can become a probelm. About 6 inches have fallen in Turnagain Pass and Girdwood in the last 24 hours. Overnight wind was strong enough to transport quite a bit of snow. Yesterday the surface snow up high was getting a “slabby” feel. Even without any prominent weak layers, recent loading has the ability to build pockets of avalanche potential.

Last night there was a natural avalanche reported near Kern creek just south of Girdwood that was large enough to affect the railroad. This underscores the potential for more avalanches to happen despite only moderate amounts of new snow. High wind yesterday played a large role in causing this avalanche.

Wind loading at higher elevation will be the most likely place to find trouble today. Expect deeper and stiffer snow on west aspects with cross loaded north and south facing slopes.

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

A series of ice crusts with associated weak layers have kept us thinking about the lower to mid elevation snowpack. A couple days ago forecasters found collapsing and unstable pit results at 1200 feet elevation. As we open the low elevation zones of Placer/Skookum and 20mile to snowmachines, this should be a concern to think about.

The Placer/Skookum/20mile zones are poorly understood at this time due to a lack of information. Expect to find moderate avalanche danger, but remember that those zones get different weather patterns and local variations may be found.

Weather

Tue, February 26th, 2013

The last few days have been consistent light snowfall with wind up high. Yesterday and overnight new snow built to around 6 inches at mid elevations in Girdwood and Turnagain, and double that amount in Grandview. Wind has gusted 40-50+ mph every hour since yesterday morning at Sunburst. Temperatures have been in the 20s at high elevation to mid 30s at sea level.

Expect more of the same weather today. A large low complex south of Kodiak is affecting our region with snowfall across the gulf coast spilling over to Turnagain Arm. Total precip will be a little less than yesterday and wind may diminish slightly as well. The forecasted snow doesn’t look like a big addition to the avalanche danger, but reduced visibility may hamper our ability to see very much today.

Graham will issue the next advisory tomorrow morning, Feb 27th

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.