Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, December 12th, 2017 - 7:00AM
Expires
Wed, December 13th, 2017 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

The  avalanche danger is HIGH  due to continued heavy rain, wet snowfall and strong winds.  A very potent warm and wet storm has saturated the snowpack and caused a natural wet avalanche cycle below 3000′. Today natural and human triggered wet slab avalanches are likely at Treeline and storm snow avalanches are likely in the Alpine. Today is a good day not to go into the mountains.  Travel in avalanche terrain is NOT recommended.  

Below 1,000′, where little snow exists, there is a  CONSIDERABLE  avalanche danger for debris running into steep or channeled terrain.

**Summit Lake also has elevated avalanche danger and the weekly summary can be found HERE.

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Tue, December 12th, 2017
Alpine
Above 2,500'
High (4)
Avalanche risk
Treeline
1,000'-2,500'
High (4)
Avalanche risk
Below Treeline
Below 1,000'
Considerable (3)
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
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Wet Loose
    Wet Loose
Wet Loose
Wet Loose avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.
More info at Avalanche.org

A series of warm and wet storms have created a widespread avalanche cycle across our forecast zone. Over the last three days 3.1 inches of rain has saturated the mid elevations (treeline zone) and rain/snow line has fluctuated between 2000’ and 3000’. A brief window of good visibility yesterday allowed for a look around Turnagain Pass where dozens of recent wet slab avalanches have occurred on all aspects below 3000’. These avalanches have been releasing near the ground on a well documented weak layer of faceted snow. The most interesting (and scary) avalanches observed yesterday were on the West facing terrain of Tincan below 2500’, an area many folks go when the avalanche danger is elevated. This avalanche cycle speaks to the powerful nature of a saturated snowpack and is a reminder that even small terrain features are suspect. An avalanche of this kind, if triggering from below or in a terrain trap, would be unsurvivable. Today another .5” of rain is expected below 2000’ combined with moderate to strong Easterly winds. High avalanche danger will continue through today and will remain elevated until the snowpack has a chance to drain or freeze. Travel in avalanche terrain is not recommended. 

Recent wet slab avalanches were observed yesterday afternoon on the West facing terrain of Tincan. 

 

 Recent avalanches on Northern and Western aspects of Corn Biscuit.

 

Dozens of slabs have ripped out to the ground on the SE face of Seattle Ridge and most of the gullies are filled with debris. As of yesterday the uptrack on Repeat Offender remained intact. 

Avalanche Problem 2
  • 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

In the Alpine, wet and heavy snow is falling, which becomes drier with elevation. From our rainfall totals at the snow stations over the last three days, we can expect around 3’ of snow has accumulated in the alpine. Cornices are building and the weak pre-existing snowpack continues to be loaded. Storm snow avalanches that include storm slabs, wind slabs and cornice breaks all can be expected today at the high elevations. This snow may also overload and tip the balance of the weak snow sitting near the ground and create a very large avalanche, taking most of the snowpack with it. This size avalanche could run into the lower elevations in steep or channelled terrain.  

Again, the message is simple for today, avoid avalanche terrain. This means steering clear of all slopes 30 degrees and steeper including your exposure to runout zones.

Weather
Tue, December 12th, 2017

Yesterday another 0.5 € of rain fell in Turnagain Pass and .94 € of rain Girdwood. Temperatures remained above freezing, mid 40F’s at seal level and mid 30F’s at 1000′. Easterly ridge top winds averaged in the 20’s with gusts in the 60’s. Temps cooled briefly last night bringing snow/rain line to 1700′ where a few inches of wet snow has accumulated at mid elevation weather stations.  

Today another 0.5 € of rain is expected throughout the day and rain/snow line is expected to be around 2000′. Easterly ridge top winds could range from 20-30mph with gusts in the 40’s. Tonight continued rain showers are expected.  

Stormy weather in the form of rain showers and strong Easterly winds is anticipated through Wednesday afternoon. Winds should diminish tomorrow afternoon and temperature will gradually start falling. Thursday into Friday we may see freezing temperatures again at sea level with a possibility of scattered rain and snow showers.  

*Center Ridge snow depth at 6am is estimated due to depth guage sensor experiencing noise.

** Sunburst weather station data is from 6am – 8pm (12/11/17) due loss of battery power yesterday evening.    

PRECIPITATION 24-hour data (6am – 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 34    3 0.5   *28  
Summit Lake (1400′) 34    0 0.1   9
Alyeska Mid (1700′) 35   2   .94   16  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) **26   **ENE   **28 **62  
Seattle Ridge (2400′) 30   ESE    21 50  
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Riding Areas
Updated Wed, December 11th, 2019

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.
Placer River
Closed
Closed.
Skookum Drainage
Closed
Closed.
Turnagain Pass
Closed
Closed.
Twentymile
Closed
Closed.
Seward District
Carter Lake
Closed
Closed.
Lost Lake Trail
Closed
Closed.
Primrose Trail
Closed
Closed.
Resurrection Pass Trail
Closed
Closed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor
Closed
Closed.
South Fork Snow River Corridor
Closed
Closed.
Summit Lake
Closed
Closed.

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