Wed, December 25, 2013 Turnagain Pass Avalanche Forecast

Wed, December 25th, 2013

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

A generally poor structure to our snowpack is keeping the persistent slab our primary concern again today. Avalanche activity appeared to peak on Sunday with two human triggered avalanches in the Turnagain area. Cold temperatures and a lack of weather today will allow our snowpack to further adjust, however it doesn’t take long to dig down to the ground to recognize the problematic weak layers that lie beneath our slow-to-build slab. Since the drizzle crust of December 7/8 (17 days ago) we have received 2.3 inches of water, which translates to about a 16-inch slab. Snow pit tests yesterday were consistently failing at this interface of faceted snow directly above the crust.

Small spells of moisture thus far have allowed our snowpack to adapt a little at a time, not overloading weak layers to the point of widespread natural avalanching yet. Add a skier or snowmachiner into the equation on steep, wind loaded terrain and producing an avalanche may be possible today. Specifically in the higher elevations where the wind has produced a deeper, heavier slab that overlies this same basic poor structure.

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

Monday morning we did have a short lived, natural wind slab avalanche cycle where strong winds proved enough to overload weak layers. In higher elevation areas it’ll be possible to find pockets of dense wind slabs 1-2’ deep on the lee side of wind-raked ridges. Pay particular attention to firm, hollow sounding snow on south, east and west aspects. These slabs may sit mid-slope given the moderate to strong winds that blew through our region on Monday and Tuesday.

Weather

Wed, December 25th, 2013

Yesterday cloudy skies in the afternoon produced just a trace of new snow in eastern Turnagain Arm as a series of low-pressure systems skirted us to the south. Winds shifted to a more easterly direction but still blew moderately yesterday. Temperatures stayed cold at sea level due to a weak temperature inversion and gradually grew warmer with elevation topping out in the low-teens on Sunburst.

Don’t expect a Christmas miracle in the form of new snow today. Rather we seem to have fallen under another persistent high-pressure ridge that appears to be with us at least until the weekend. There is a decent temperature inversion in place this morning with temps ranging from 2 degrees in Portage to 20 degrees at the top of Sunburst. Winds appear to again shift back to a northwest orientation today blowing in the 10-20mph range.

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.