Thu, January 30, 2014 Turnagain Pass Avalanche Forecast

Thu, January 30th, 2014

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

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 don’t have a lot of information about the high elevation deep slab because so few people have been traveling in the mountains over the last couple weeks. Yesterday on Seattle ridge we dug in a deeper area at 2900 feet and found 5 feet of mostly very strong snow on top of the old Nov/Dec persistent weak layers. (click on link for photos and pit profile) We could not get an extended column test to fail, but 2 compression tests revealed sudden collapse Q1 failures at the early December drizzle crust (CT24, CT21 Q1). The good news is that our recent wet storm has made some very strong snow – it’s difficult to cut through it with a sharp saw. I think it will be unlikely for a person to trigger the deep weak layers where the snowpack is in fact deep. It may be possible to trigger from shallow points where it could propagate to much deeper snow.

Avalanche Problem 2

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

I’m still going to mention wet avalanches even though we now have a surface crust over everything. You have to dig through the crust to find the wet snow.

If someone were to trigger an avalanche below 3,000 feet, it will have some characteristics of a wet slab. Think about heavy, slow moving, bulldozer-like avalanches.

We dug a shallow pit just off the slope from the standard snowmachine up-track to Seattle ridge yesterday. Underneath the 4 inch think supportable crust is unbelievable weak, moist snow. Skis glide over the crust with no penetration, but trying to walk on it will sometimes punch a boot through the crust, which then drops through to the ground. It’s a very abnormal setup, and I’m honestly not sure how to measure its stability.

As more of the snowpack freezes up with the colder temperatures, strength will increase quickly and the possibility of triggering more avalanches in the wet snow will decrease dramatically.

Weather

Thu, January 30th, 2014

Sunny breaks over the last few days will continue today. Southcentral Alaska is dominated by a blocking high pressure that is currently keeping clouds and storm from the west from entering our airspace. The big weather change that is affecting our snowpack is a drop in temperature. Ridgetop stations have been reading below freezing for over 48 hours. Lower elevation sites are now also freezing up. Wind is light and variable today.

Looking into the weekend – high pressure is expected to be the dominating feature for our region. Mostly clear skies are forecasted, with valley fog in some areas.

Graphs show the temperature profile at Center Ridge (1880 ft) and Sunburst (3812 ft). Blue line is 32 degrees (freezing).

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
05/18/21	Turnagain	Observation: Tincan Ridge	Joe Kurtak
04/30/21	Turnagain	Observation: Sunburst	W Wagner Forecaster
04/27/21	Turnagain	Observation: Tincan Ridge	Joe Kurtak
04/26/21	Turnagain	Observation: Magnum	Creighton/ Hoople
04/25/21	Turnagain	Observation: Sunburst	Nick D'Alessio
04/24/21	Turnagain	Observation: Airplane obs	Johnston-Bloom / DiJulia /Hilliard Forecaster
04/24/21	Turnagain	Observation: Corn biscuit	Heather Johnson
04/23/21	Turnagain	Avalanche: Lynx Ck Drainage	W Wagner Forecaster
04/23/21	Turnagain	Avalanche: Sunburst	Eeva Latosuo
04/23/21	Turnagain	Observation: Center Ridge Turnagain pass	Joe Kurtak

Riding Areas

Updated Tue, June 01st, 2021

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
Placer River	Closed	It is packrafting and jetboat season!
Skookum Drainage	Closed	The Skookum Valley is closed to snowmachines. This closure occurs annually on April 1 as per the CNF Forest Plan.
Turnagain Pass	Closed	Closed as of June 1. 188 day season, that\'s a wrap!
Twentymile	Closed	It is packrafting and jetboat season!
Seward District
Carter Lake	Closed	Closes May 1.
Lost Lake Trail	Closed	Closes May 1.
Primrose Trail	Closed	Closes May 1.
Resurrection Pass Trail	Closed	Closed for the 2020/21 winter season. Will be open for moto use in the 21/22\\\' winter season as per the CNF Forest plan.
Snug Harbor	Closed	Closes May 16th.
South Fork Snow River Corridor	Closed	Closes May 1.
Summit Lake	Closed	Closes May 1.