Sat, March 22, 2014 Turnagain Pass Avalanche Forecast

Sat, March 22nd, 2014

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

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

This problem is increasingly becoming unlikely, but the hazard associated with it could be dangerous if triggered. The storm snow from last week has now settled to about 3+ feet of hard consolidated snow. This slab is strong and difficult to trigger, but it sits at an interface that sometimes shows poor bonding to the older layer below it.

The deep slab is most likely to be triggered from a shallow area where the slab tapers down to 1 foot deep or less. Alternatively a large trigger like multiple skiers or a snowmachine could initiate through a deeper portion of the slab.

Photo – Typical steep terrain with deep slab avalanches evident from the storm and large cornice features.

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

We got a report of a small wind slab triggered in Pastoral a couple days ago. Click here for observation. An east wind was loading up westerly aspects. Today it is possible to find stiff aging wind slab that could pop when traveled on. Keep this in mind, especially in steeper terrain.

Additional Concern

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

Cornices are big and mature this time of year. As people get onto steeper terrain the cornice factor becomes more significant. In some steep areas they are a mandatory nuisance to be negotiated.

Remember to scope out a safe entrance that avoids a blind approach onto overhanging cornice features. Take a rope for a safe belay if you think your chosen line can’t avoid cornice exposure.

Weather

Sat, March 22nd, 2014

The last storm ended more than a week ago. High pressure and sunny skies have dominated the weather pattern since then. We had some moderate wind on Thursday that blew some snow around.

We are looking at another calm sunny day ahead of us. Temperatures will start out cold this morning, ~10 degrees at valley floor and ~20 degrees at the ridgetops. The sun will quickly warm things up to the high 30s in the afternoon. East wind to 10mph.

Sun will stay in the forecast into mid week. No major storms are on the horizon as the Rex block continues to dominate weather over Alaska.

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
11/28/22	Turnagain	Observation: Pastoral	Schauer/ Wadsworth Forecaster
11/27/22	Turnagain	Avalanche: Tincan	Anonymous
11/26/22	Turnagain	Observation: Eddies	Schauer/ Cullen Forecaster
11/26/22	Turnagain	Observation: Eddies	Andy Moderow
11/26/22	Turnagain	Observation: Lipps	Big Ripper
11/25/22	Turnagain	Observation: Sunburst	Hannah Smith
11/25/22	Turnagain	Observation: Sunnyside / Seattle Ridge	Matti Silta
11/25/22	Turnagain	Observation: Sunburst	John Sykes
11/25/22	Turnagain	Observation: Tincan Trees	Andy Moderow
11/25/22	Turnagain	Observation: Tincan	Galen Hecht

Riding Areas

Updated Wed, November 30th, 2022

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	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Placer River	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Skookum Drainage	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Turnagain Pass	Closed	The Forest has issued a closure order for Turnagain Pass due to inadequate snow cover for resource protection. Conditions will be monitored daily. Between 14-16” of snow exists at the parking lot. The scheduled opening would have been the Wednesday before Thanksgiving per Forest Plan.
Twentymile	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Seward District
Carter Lake	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Lost Lake Trail	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Primrose Trail	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Resurrection Pass Trail	Closed	Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
South Fork Snow River Corridor	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Summit Lake	Closed	The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.