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Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, March 1st, 2013 - 7:00AM
Expires
Sat, March 2nd, 2013 - 7:00AM
Forecaster
Kevin Wright
The Bottom Line

Still within 48 hours of a significant storm event, caution is warranted in the backcountry.   Some areas received over 2 feet of snow in the latest storm.   A handful of large and destructive avalanches were caused by this storm in the last few days.   Above treeline the danger will be MODERATE for storm snow, wind slab, and cornices.  

The backcountry stability is on a steady improving trend.   Natural avalanches are unlikely, human triggered avalanches are possible in specific steeper terrain.  

Watch for lower elevation south facing slopes to become active if temperatures rise this afternoon.

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Fri, March 1st, 2013
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Moderate (2)
Below Treeline
Below 1,000'
Avalanche risk
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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 recent storm had peak intensity 2 days ago, and dropped more than 2 feet of snow in some areas including Turnagain Pass.  It was deep enough on Wednesday to make travel downhill quite difficult.  After yesterday’s relatively clear weather that snow should be settled and consolidated to the point that travel is easier. 

A handful of large avalanches were caused by that storm, including a large natural that crossed the Portage road.  All the major avalanche programs in our region were doing explosive avalanche reduction work.  After the storm ended yesterday, explosive triggers were only causing small to medium avalanches occasionally, with nothing deeper than the recent storm snow.  The picture below shows one of the larger avalanches produced by Seward highway work yesterday. 

Colder temperatures and calmer weather will be acting to bring stability to the recent storm snow, but it still deserves a cautious approach today.

Avalanche Problem 2
  • Persistent Slabs
    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

The larger avalanches that we’ve seen this week are suspected to be a result of deeper weak layers at the late January crusts.  The good news is it remains a less likely problem to encounter.  The bad news is it remains a tough problem to predict and avoid 100% of the time, even for the experts.

The buried crusts can be found in some areas at mid elevations between roughly 1900 and 3000 feet.  As those layers get deeper with each storm, the likely places to trigger deeper layers will be from shallow points that have been partially scoured by wind.

 

Weather
Fri, March 1st, 2013

Storm totals yesterday morning reached near 2 feet of snow and up to 2 inches of water equivalent in some areas.   Areas such as Girdwood, Grandview, and Portage got more snow.   Summit lake got less, but still enough to cause concern.  

In the last 24 hours temperatures have cooled off a few degrees, wind has dropped, and precipitation ended by the afternoon.  

Today, a weak low pressure is spinning in Prince William Sound which may bring a few inches of snow.   Snowfall will end tonight and the weekend will bring a clearing trend.   Expect temperatures in the 30s and light wind.  


Fitz will issue the next advisory Saturday morning, March 2nd.

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Riding Areas
Updated Fri, May 01st, 2020

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
Placer River
Closed
Skookum Drainage
Closed
Turnagain Pass
Closed
Closed as of May 1. Thanks for a fun, safe season!
Twentymile
Closed
Seward District
Carter Lake
Closed
Lost Lake Trail
Closed
Primrose Trail
Closed
Resurrection Pass Trail
Closed
Snug Harbor
Closed
South Fork Snow River Corridor
Closed
Summit Lake
Closed

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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.