Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, November 23rd, 2012 - 7:00AM
Expires
Sat, November 24th, 2012 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

We are issuing advisories 5 days a week through November on Sat, Sun, Tue, Thur and Fri.

BOTTOM LINE

The avalanche danger will remain CONSIDERABLE today on slopes steeper than 35 degrees above 3000′ and on all aspects. Recent natural avalanches in this terrain points to the continued instability of the snowpack. Slopes most likely to be triggered will have a slab of stiff snow overlying weak snow near the ground.   Safer slopes are those lacking a slab and consist entirely of weak snow (making hitting rocks more likely). Below treeline, there is minimal snow cover that does not have the structure of the higher elevations and has a LOW avalanche danger.

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Fri, November 23rd, 2012
Alpine
Above 2,500'
Considerable (3)
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
Considerable (3)
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
  • 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

With little change in the weather, we had yet another natural avalanche release in the heart of Turnagain Pass sometime late on Wednesday, Nov. 21st , or early yesterday morning. This was on the SW face of Sunburst – photo below and more details HERE. The slide was believed to be triggered by a slight bump in wind that loaded the slope and tipped the balance. The loading was minimal, demonstrating the precariousness of the pack. It is events like this that is keeping us on our toes.

Good travel practices are essential right now. We have seen 5 natural avalanches the past 4 days and heard of 0 human triggered avalanches (the past 4 days). I believe this is attributed to folks managing their terrain with lower slope angles and looking for areas where the snow cover is entirely weak snow (sugar) and lacking a slab. Suspect slopes are those with supportable stiffer snow over weaker hollow snow and are to be avoided. As we have mentioned, a ride down one of these rocky bed surfaces if caught could get ugly. Straying a bit from the established skin track and feeling for collapsing and cracking as one travels is a good way to gain a sense of the snowpack.

The weak snow from October continues to plague us and the past several days of cold and clear weather is not helping to strengthen it. But, what the weather has been doing is actually weakening the strong layer (the slab). If the slab becomes weak enough (through faceting) the snow cover will change back to one layer of loose sugary snow. In this case, the avalanche danger decreases substantially until it gets covered by the next bout of snow and/or wind. This process has already occurred on certain slopes, making them safer than they were one or two weeks ago.

Below treeline, the structure of a slab over weak snow is not present. The pack here consists mostly of 12-24″ of loose weak snow with a crust layer about 8-10″ down from the surface (formed by the rain and wet snow on Nov 2nd).

Weather
Fri, November 23rd, 2012

Two words: clear and cold. The single digit temperatures that have been pooling in our low elevations and parking lots will remain in place for the next several days.  The good news is warmer air, in the mid 20’s, sits just above the inversion on the ridgelines. The northerly winds that picked up yesterday have decreased and should blow around 5mph from a northerly direction today. As for snow, there is a chance we may see some flurries fall the middle of next week. Other than that it looks bleak.


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).  

Kevin will issue the next advisory Saturday morning, November 24th.  

Observations
Recent Observations for Turnagain Pass
Date Region Location
05/21/22 Turnagain Avalanche: Magnum, Lipps and Tincan
05/17/22 Turnagain Avalanche: Sunburst
05/17/22 Turnagain Observation: Tincan Ridge
05/11/22 Turnagain Avalanche: Cornbiscuit and Magnum west faces
05/07/22 Turnagain Observation: Granddaddy
04/29/22 Turnagain Observation: Sunburst wx station
04/28/22 Turnagain Observation: More Turnagain Pass/Summit Lake wet slab activity
04/27/22 Turnagain Observation: Magnum
04/27/22 Turnagain Observation: Girdwood/Summit/Turnagain Road obs
04/24/22 Turnagain Avalanche: Seattle Ridge – large glide avalanche on Repeat Offender path
Riding Areas
Updated Fri, May 13th, 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
Closed as of May 1 per Forest Plan.
Placer River
Closed
Closed as of April 25th due to insufficient snow coverage.
Skookum Drainage
Closed
Closed as of April 1st per Forest Plan.
Turnagain Pass
Open
Open. Extended opening through May 31.
Twentymile
Closed
Closed as of April 6th due to insufficient snow coverage.
Seward District
Carter Lake
Closed
Closed as of May 1 per Forest Plan.
Lost Lake Trail
Closed
Closed as of May 1 per Forest Plan.
Primrose Trail
Closed
Closed as of May 1 per Forest Plan.
Resurrection Pass Trail
Closed
Closed as of May 1 per Forest Plan.
Snug Harbor
Closed
Closed as of May 1 per Forest Plan.
South Fork Snow River Corridor
Closed
Closed as of May 1 per Forest Plan.
Summit Lake
Closed
Closed as of May 1 per Forest Plan.

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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.