Thu, January 22, 2015 Turnagain Pass Avalanche Forecast

Thu, January 22nd, 2015

Alpine
Above 2,500'

Moderate (2)

Treeline
1,000'-2,500'

Low (1)

Below Treeline
Below 1,000'

No Rating (0)

Alpine Above 2,500'		Moderate (2)
Treeline 1,000'-2,500'		Low (1)
Below Treeline Below 1,000'		No Rating (0)

Danger Scale:

No Rating (0)

Low (1)

Moderate (2)

Considerable (3)

High (4)

Extreme (5)

Avalanche Problem 1

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

Today we are expecting 2-4″ of new snow above 1000’, with an addtional 3-6″ arriving later today and into this evening. This morning ridgetop winds have picked up to 15-25mph from the East and are expected to remain moderate throughout the day. This could be just enough wind and new snow to form tender wind slabs (4-10”) in upper elevations above 2500′.

These wind slabs could be easily triggered on steep features (>35°) like convexities, along gullies, or just below a steep ridgeline. Pay attention to leeward slopes that are loading and make a note of how much snow is falling throughout the day.

Over the last few days’ cold temperatures have been weakening the surface snow by creating near surface facets. 2-6″ of poorly bonded snow crystals are sitting on top of a firm bed surface (a dense wind slab at elevations above 3000’ and a melt/freeze crust at lower elevations.) This set up is less than ideal as we go into a storm cycle – depending on how the storm arrives this could be our next weak layer to track in the coming days.

Avalanche Problem 2

Cornice

Cornice

Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.

More info at Avalanche.org

Many cornices have formed along ridgelines in the alpine throughout Turnagain Pass and Girdwood. These large unsupported snow formations are difficult to see sometimes or until you’re too close for comfort. Be aware of areas that have well formed cornices and give them extra space if you plan to travel along a ridgeline.

Additional Concern

Glide Avalanches

Glide Avalanches

Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.

More info at Avalanche.org

We have been continuing to monitor glide activity over the last week, with the most recent glide avalanche occurring several days ago on the South Face of Eddies. Glide cracks are unpredictable and it can be challenging to understand the exact nature of what triggers a glide to release. It is best to avoid traveling under or on slopes with large crevasse looking cracks.

Weather

Thu, January 22nd, 2015

Yesterday skies were clear, winds were light, 5-10mph, shifting from the East to the West throughout the day. Valley fog kept temperatures in the single digits (6-10F) at lower elevations with ridgetops reaching low 20’s F.

As of early this morning ridgetop winds have picked up to 15-25mph from the East and temperatures have also started to increase at upper elevations (low 20’sF.) No new precipitation was recorded in the last 24 hours.

Today 2-4 € inches of snow is expected this afternoon with an additional 3-6 € into the evening. Ridgetop winds are expected to remain moderate (15-20mph) throughout the day with temperatures steadily increasing to 30F.

More snow, up to 6 € is forecasted for Friday. Temperatures should remain in the upper 20’sF to low 30’sF and ridgetop winds are expected to be light to moderate.

*Seattle Ridge wind speed data was unavailable until 4am this morning. The below average/gust/dir are from 4am – 6am today.

PRECIPITATION 24-hour data (6am – 6am)

	Temp Avg (F)	Snow (in)	Water (in)	Snow Depth (in)
Center Ridge (1880′)	16	0	0	30
Summit Lake (1400′)	9	0	0	6
Alyeska Mid (1700′)	15	0	0	19

RIDGETOP 24-hour data (6am – 6am)

	Temp Avg (F)	Wind Dir	Wind Avg (mph)	Wind Gust (mph)
Sunburst (3812′)	20	Var	7	27
Seattle Ridge (2400′)	15	*ENE	*16	*34

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.