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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, January 16th, 2013 - 7:00AM
Expires
Thu, January 17th, 2013 - 7:00AM
Forecaster
Kevin Wright
Avalanche risk The Bottom Line

With calmer weather, colder temperatures, and less recent evidence of avalanche activity the danger rating drops to MODERATE today for the first time since December 23rd.   A significant amount of uncertainty still exists, and if an avalanche is triggered it may still be very large and dangerous.   Below treeline the danger is LOW.

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Wed, January 16th, 2013
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
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 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 is still the deep slab problem.  Just two days ago we had a number of very large avalanches, both in Turnagain Arm and Turnagain Pass.  Since that time the rain and snow stopped and the temperature dropped significantly.  Yesterday, just one day removed from the storm, a number of explosive triggers in Turnagain Arm had few significant results. 

The majority of the avalanche activity from the final burst of moisture seemed to be focused on steep, rocky terrain.  This gives us a good starting point on which to base our terrain choices.  The weak layer that may collapse to intiate an avalanche is unlikely to be affected by a skier in areas of deeper snow.  The likely “trigger points” will be shallower, where the stress of a person doesn’t have to penetrate through as much strong snow.  Steep north facing lines, complex terrain with chutes and ribs, and generally shallower areas should be avoided today.  This problem should be approached by traveling where the snow is deepest, and testing it where it is thinnest to gauge the worst case scenario.

Yesterday our pit tests on Sunburst found the same weak base layer that has plagued us for most of the season.  The general feel of the layering structure isn’t much different from what we’ve been seeing.  However, the force require to initiate a collapse was significantly greater than it was a week ago.  The bad news is that it still collapses, and it still propagates.  This tells us that triggering a collapse is less likely, but if it happens, a large avalanche is still very possible. 

Pictured below is the before and after of Alpenglow peak which slid on Monday.

 

Avalanche Problem 2
  • Wind Slabs
    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

Above treeline there was wind during the last storm system.  Ridges have a stiff, windblown character to them.  Deeper and stiffer snow will be found on the lee side of terrain features.  We don’t have a lot of evidence to suggest that windslabs will be unstable, but it is something to watch out for. 

Weather
Wed, January 16th, 2013

The last major storm system left us on early Monday, giving us more than 48 hours since significant precipitation.   Temperatures have dropped since that time, freezing the rain and wet snow that fell below 2000 feet into a surface crust.  

Today, 3-5 inches of snow is in the forecast with light wind.   Temperatures should remain below freezing.   The weather today is not expected to contribute much to the avalanche problem.  

Observations
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Riding Areas
Updated Fri, January 06th, 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
Open
Opened Dec 13th.
Placer River
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Skookum Drainage
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Turnagain Pass
Open
Opened Dec 13th.
Twentymile
Closed
Closed Jan 5th due to lack of snow (holiday storms rained away the snow at sea level).
Seward District
Carter Lake
Open
Opened Dec 13th.
Lost Lake Trail
Open
Opened Dec 13th.
Primrose Trail
Open
Opened Dec 13th.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Open
Opened Dec 13th.
South Fork Snow River Corridor
Open
Opened Dec 13th.
Summit Lake
Open
Opened Dec 13th.

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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.