Sat, January 19, 2013 Turnagain Pass Avalanche Forecast

Sat, January 19th, 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

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

The primary concern today is still the deep slab, which is becoming more stable over time. We haven’t had reports of deep slab avalanches since Monday when the last storm system ended. The snowpack is showing evidence of strengthening, but a number of tests consistently still show a low probability of initiating a large avalanche.

This kind of deep slab problem needs to earn our trust. We have growing confidence, but only to a certain point. The consequences of causing a full depth avalanche still deserve our respect and some alteration in our terrain choices. Areas with thinner snow cover are more suspect, and steep rocky terrain may hold the trigger points that could activate a large avalanche.

Now that the deep weak layer has been dormant for a few days we can expect a low possibility of triggering it. A new significant snow load (which is in the weather forecast for tonight) will increase the chances of deep slab activity as additional stress gets added to the weak foundation (see picture below).

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

The small amount of snow predicted to fall this afternoon will build wind slabs at higher elevations. Based on the timing of this storm it looks like this problem will be minor today, but may build into a significant problem tomorrow.

Weather

Sat, January 19th, 2013

A blizzard watch is in effect for Girdwood, Seward, and Whittier starting this evening. It appears that this will not have a major effect on the daylight hours today, but it may cause a bump in the avalanche danger by tomorrow. We can expect increasing wind and up to 5 inches of snow by this evening.

If you are wondering how the mountains are doing for snow this year check out the graph below. Our snow depth is slightly above average, and the Snow Water Content measured at 1880 feet at Turnagain Pass (below) is just barely below average.

SWE

Observations

Recent Observations for Turnagain Pass

Date	Region	Location	Observer
01/23/22	Turnagain	Observation: Pete’s North	Sykes / Sullivan / Stiegel Forecaster
01/23/22	Turnagain	Observation: Cornbiscuit west shoulder	Doug Dog Loso
01/21/22	Turnagain	Observation: Tincan	Sykes / Mehl
01/20/22	Turnagain	Avalanche: Tincan Proper	Anonymous
01/20/22	Turnagain	Observation: Super Bowl	Schauer/ Rothman Forecaster
01/20/22	Turnagain	Avalanche: Tincan	Kit Barton
01/20/22	Turnagain	Avalanche: Eddies	Andy Moderow
01/19/22	Turnagain	Observation: Lynx Creek	Sykes / Schauer Forecaster
01/19/22	Turnagain	Avalanche: Pete’s North	Anonymous
01/17/22	Turnagain	Observation: Lipps	Sykes / Vantrease / Cronick Forecaster

Riding Areas

Updated Wed, December 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	Open	Open as of Dec 1st.
Placer River	Open	Open as of Dec 1st. Limited parking due to Portage curve construction.
Skookum Drainage	Open	Open as of Dec 1st. Limited parking due to Portage curve construction.
Turnagain Pass	Open	Open as of Saturday, Nov 27. Be aware of early season hazards (alders/creeks) and open water.
Twentymile	Open	Open as of Dec 1st.
Seward District
Carter Lake	Open	Open as of Dec 1st.
Lost Lake Trail	Open	Open as of Dec 1st.
Primrose Trail	Open	Open as of Dec 1st.
Resurrection Pass Trail	Open	Open as of Dec 1st.
Snug Harbor	Open	Open as of Dec 1st.
South Fork Snow River Corridor	Open	Open as of Dec 1st.
Summit Lake	Open	Open as of Dec 1st.