Sun, February 02, 2014 Turnagain Pass Avalanche Forecast

Sun, February 2nd, 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

We have relatively little information from the last 5 days because so few people are getting into the backcountry right now. Conditions are challenging with a hard “chattering” crust below treeline that is a prerequisite before you gain the slightly softer zone above treeline.

The last major high elevation deep slab that we know of was a week ago on Goat Mountain in the Girdwood valley. Remember that this problem doesn’t stabilize quickly like a storm slab problem.

Above treeline the snowpack is thick, with weak snow at and near the ground. We have been able to cause failures on these layers in test pits.

Managing this low likelihood, high consquence problem can be accomplished by limiting travel in steep terrain. If that isn’t an option, then exposing one person at a time to steep terrain will reduce risk exposure.

Avalanche Problem 2

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 wind has been limited, so wind slabs are generally older. Above treeline there can be found some soft snow and some wind stiffened snow. Watch out for pockets of stiff wind slab that may fail in small avalanches. Unstable cornices are another subcategory that fits into wind slab concerns.

Additional Concern

Announcement

Announcement

More info at Avalanche.org

Wendy posted this summary yesterday, which gives us a good look at the recent weather.

With many days of unseasonably warm weather during January, some of us are wondering just where did we stack up in the monthly averages. There is more data to crunch so stay tuned – but we do have a few sets of interesting numbers. Below are graphs of precipitation, SWE (Snow Water Equivalent) and Temperature.

Weather

Sun, February 2nd, 2014

We have not had any significant precipitation for the past week.

Current weather has a temperature inversion across the region. Sea level temperatures are in the mid to high teens, ridge top temperatures are in the high 20s. Valley fog has dominated Turnagain Arm for a few days, and this will likely continue today. Wind has been light for several days now. These conditions are building surface hoar crystals, which could become a buried weak layer the next time it snows.

The blocking high pressure pattern is expected to continue this week. By the end of the week – computer models are showing a pattern change but the exact nature of that weather remains uncertain.

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.