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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, March 11th, 2014 - 7:00AM
Expires
Wed, March 12th, 2014 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

The  avalanche danger is  HIGH in the mountains surrounding the Eastern Turnagain Arm. Upwards of 20-24″ of snow has fallen since yesterday morning and another 7-10″ is on tap for today. Large natural avalanches are likely and human triggered avalanches are certain due to the rapid loading by the new snow and strong Easterly wind.  The new snow is falling on a very weak preexisting surface which is expected to enhance avalanche activity.  

AN AVALANCHE WARNING IS IN EFFECT FOR TODAY AND WILL EXTEND THROUGH MIDNIGHT TONIGHT.

**Dangerous avalanche conditions exist in the backcountry. Travel in avalanche terrain is not recommended. This includes all slopes steeper than 30 degrees. Avoid terrain traps, such as gullies and tree wells and steer well clear of runout zones.

Avalanches may be triggered remotely from the side, top or from below. Treed locations have many terrain traps that can pose a serious threat today.

Special Announcements

The Alaska DOT Avalanche Program will be conducting avalanche hazard reduction work on the Seward Highway  and Portage Road today – expect delays. Check 511.gov for more details.

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Tue, March 11th, 2014
Alpine
Above 2,500'
High (4)
Avalanche risk
Treeline
1,000'-2,500'
High (4)
Avalanche risk
Below Treeline
Below 1,000'
High (4)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
High (4)
Treeline
1,000'-2,500'
Avalanche risk
High (4)
Below Treeline
Below 1,000'
Avalanche risk
High (4)
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

Well, it sure looks like winter is taking a 3rd stab at coming to Southcentral Alaska this season. After a high and dry couple of weeks (not to mention our thin snowpack that sits roughly ~40% of average) we are now entering into a stormy weather pattern. Due to the meager snow year, we have been plagued with several weak layers in the snowpack. The most concerning one for this storm cycle is the preexisting snow surface. Before snow began to fall yesterday, we had a mix of 1-2″ of faceted snow and surface hoar sitting on a variable 1-4″ crust (for a better look at this check out Fitz’s video from Sunday). This is a classic weak layer and bed surface combo that now has a 2-3′ slab on top.

During our field day yesterday only 6-8″ of snow had fallen yet we were able to find and easily trigger a slab avalanche 10-14″ thick on a wind loaded slope (photo below).  This is a look at things to come. With up to 2′ of storm snow currently and more on the way, slab avalanches up to 2-3′ deep, or deeper in wind loaded locations, are likely. Additionally, the weak snow underneath adds to the potential for slabs to propagate around terrain features and possibly break where you may not expect them to.

Photo: Human triggered slab avalanche in the Tincan Trees, ~1,700′ elevation, West facing.

 

For today, avoiding avalanche terrain is recommended due to the high volume of heavy snow sitting on a weak surface. Again, avalanches have the ability to propagate wider than expected and can be triggered remotely; this includes from below. Even “in the trees” avalanche terrain exists and there are dangerous terrain traps under small steep slopes/cliffs.

Weather
Tue, March 11th, 2014

Since 7am yesterday, heavy snowfall has deposited 20+ inches in the mountains around the Eastern Turnagain Arm. Winds were strong from the East with this “Chugach Special” and averaged in the 50-70mph range with a max gust at the Sunburst station of 114mph! Snowfall has tapered off overnight along with the Easterly winds, which are now blowing 20-30 with gusts to 50mph. The rain/snow line crept up from sea level to around 1,000′ overnight along with the ridgetop temperatures which have risen from ~20F to the mid 20’sF.

Storm totals (7am yesterday to 6am today – check this out on the Turnagain Pass snow stake loop!):
Turnagain Pass, 1880′ elev – 20″ snow (1.6″ water equivalent)
Girdwood Valley, 1700′ elev – 21″ snow (1.6″ water equivalent)
Summit Lake, 1400′ elev – 8″ snow (.6″ water equivalent)

An additional 7-10″ of snow (~.7″ water) is on tap today as the remnants of the large low pressure system continues to spin South of the Kenai pushing moisture our way. The Easterly winds are also expected to bump back up today into the 50mph range with higher gusts. Temperatures are expected to remain in the mid 20’sF on the ridgelines and the rain/snow line hover near 1,000′.

Looking forward: The weather models are showing a break in storms late tonight through Wednesday before another – and very similar – low pressure tracks through Thursday/Friday. This should bring another decent shot of precip our way.

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.