Tue, December 04, 2012 Turnagain Pass Avalanche Forecast

Tue, December 4th, 2012

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

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

With unrelenting cold and calm weather, our shallow snowpack continues to degrade into weak, sugary snow exposing more rocks daily. At the upper elevations this process has been slower and a poor snowpack structure persists in certain areas, which is our primary concern. Though the only avalanche activity we have heard of or seen for the past 10 days has been sluffs in the weak snow, there is still a concern a slab could be triggered breaking in the old October facets near the ground.

Snowpack observations from yesterday from two notorious upper elevation starting zones point to a steady decline in the potential to trigger one of these slabs. The most concerning places to trigger a slide are those with little or no previous traffic. There are many slopes that remain untouched due to difficult early season/low snow cover access.

Snow surface conditions:
There is a very thin layer of dust on the snow surface that is believed to have been deposited sometime on Friday/Saturday by the strong winds channeled through the Mat-Su Valley. The high winds likely entrained particles that were then carried by the NW winds through Turnagain Arm and deposited in our forecast zone. The dust on snow became more visible with elevation yesterday.

Above treeline a scattered thin wind crust can be found on the loose snow surface in exposed areas. Below treeline there is still very loose, unsupportable snow which is sitting under some quite impressive surface hoar growth.

Sidenote: With the earthquake yesterday evening, I’m wondering (or more accurately hoping) if any facets were shaken off the slopes?

Weather

Tue, December 4th, 2012

Mid-level clouds moved in from the east yesterday associated with a multipart low pressure system spinning in the Gulf and even dropped a flake or two on Turnagain Pass. The clouds look to have reminded overnight and despite the cover, which helps to €œhold the heat in €, temperatures have decreased to a new seasonal low at all elevations, except sea level. Ridgetop weather stations are reporting -4 to 0F while treeline stations are -2 to 3F. The inversion is still firmly in place with sea level and valley bottoms in the -15 to -10F range. Expect clearing skies and temperatures to rise 5 degrees or so throughout the day. Ridgetop winds are luckily still light from the northeast, 2-5mph gusting 5-10mph, where they should remain today.

We are still waiting for snow and looking at the longer term model forecasts in hopes of seeing a €œfire hose € of moisture pointed at us. Unfortunately, we are going to have to keep waiting through the week – but it does look like there is hope for Saturday. It may not be the fire hose we want, but at least it is a substantial change in the pattern and we should finally see some precipitation.

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).

Kevin will issue the next advisory Wednesday morning, December 5th.

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.