Tue, January 28, 2014 Turnagain Pass Avalanche Forecast

Tue, January 28th, 2014

Alpine
Above 2,500'

Considerable (3)

Treeline
1,000'-2,500'

Considerable (3)

Below Treeline
Below 1,000'

Considerable (3)

Alpine Above 2,500'		Considerable (3)
Treeline 1,000'-2,500'		Considerable (3)
Below Treeline Below 1,000'		Considerable (3)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

Wet Loose

Wet Loose

Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

More info at Avalanche.org

Despite the impressive spike in temperature yesterday at the ridgetops, we did not see or hear of any new avalanche activity. There were a few small wet point releases and one potential small slab in the Summit Lake area that may have occurred. Our last known wet slab was on Turnagain Pass Sunday – two days ago. Photo below.

One thing we have different today is a substantial drop in temperature. This is good news, both for stabilizing the snowpack as well as limiting the melt-out seen below treeline. However, temperatures are still warm in the big picture and though the snowpack continues to season and adjust to the warm conditions, large wet avalanches are still possible.

Below is the last known wet slab avalanche. It occurred Sunday, January 26th on Pete’s South ridge – South side of Turnagain Pass.

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

At the upper elevations (above 3,500′ or so) where snow has been falling for almost two weeks now the snowpack has been getting deeper by the day. We had evidence of a large deep slab avalanche cycle last week, with the last known deep slab three days ago on Goat Mtn. Though it has been a few days since we’ve seen or heard of any new deep slabs, it doesn’t mean the problem has gone away. The pack dealt with a large spike in temperature yesterday (over 40F at 4,200′) and has seen persistent strong wind for over a week. It is not likely anyone will be traveling in this upper elevation terrain, but the possibility exists for natural avalanches to occur and run to valley bottoms.

Additional Concern

Announcement

Announcement

More info at Avalanche.org

A few comments on the state of the snowpack:

Below treeline – the pack is completely wet, unsupportable (mush) and melting out. The Turnagain Pass SNOTEL at 1880′ is reporting 29″ depth (average for the past nine years of available data is 73″). Click here for a few more details and pictures.
Above treeline – the pack starts with around 40″ of wet snow at treeline and becomes much deeper and dryer with elevation. Around 4,000′ and higher the snow is dry enough that wind is able to produce plumes.

All that said, there is still a layer of weak faceted snow that sits near the ground and is responsible for our many slab avalanches seen so far this season. Depending on elevation, the faceted snow is either wet (below treeline) and melting or dry (well above treeline) and being compressed with the weight of the new snow from the past couple weeks.

Below treeline (Turnagain Pass looking Northeast) Above treeline (South end of Pass looking North at Pk 4940)

Weather

Tue, January 28th, 2014

During the past 24-hours we have seen a significant drop in temperature since yesterday morning’s spike (to the low 40’s F on the ridgetops and mid 50’s at sea level). We are now sitting in the upper 20’s at the ridgetops and around 40F at sea level. Winds were averaging 50mph yesterday but have dropped to 10mph overnight from the East. We had .4″ of rain to 3,500′, mostly falling in the afternoon.

Today we should see the remnants of yesterday’s system move out. Light rain up to 1,500′ is expected to fall during the day with around .2″ accumulating. Skies should be mostly cloudy and could clear up a bit by the afternoon. Temperatures will be in the upper 20’s on the ridgelines and near 40F at sea level. Winds are expected to remain light from the East in the 10mph range.

For tomorrow we should see conditions similar to today but for Thursday a cooling and clearing trend looks to develop.

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.