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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sun, January 15th, 2017 - 7:00AM
Expires
Mon, January 16th, 2017 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

The avalanche danger is MODERATE today in the mountains surrounding Turnagain Pass at elevations above 1,000′ and on all aspects. Wind slab avalanches will be possible to trigger on slopes over 35 degrees that have been loaded by winds. These slabs are expected to be relatively soft, in the 1-2′ thick range and could be lower on slopes due to cross-loading. Loose snow sluffs are also possible on the steeper slopes and these could run further than expected.  

*In the Girdwood Valley, where more snow fell on Friday, there is a heightened danger as a slab avalanche triggered could be 2-3′ thick on wind loaded slopes.  

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Sun, January 15th, 2017
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
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
Moderate (2)
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
  • 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

It feels like a return to “what winter should be like” along the Eastern Turnagain Arm this weekend. Snow has been consistently falling after a two week dry spell, and to sea level for the first time in practically 4 years. Friday’s snowfall numbers were confirmed yesterday to be 8-12″ at Turnagain Pass, 7″ at Johnson Pass, 7″ at Ingram Creek at sea level and the winner, 15-18″ in Girdwood Valley. Another round of snow is on the way currently and is expected to bring 2-3″ today and another 4-6″ tonight, at all elevations. These may not be the heavy Chugach Storms, but they are drastically improving riding and skiing conditions.

Avalanche activity yesterday, that we know of, was minimal. Human triggered sluffs and very small slabs were noted. Poor visibility limited a good look around for assessing natural avalanches that may have occurred during the storm. We had a number of folks mention ‘possible crowns’ seen on N facing Sunburst, NE facing Tincan (Todd’s Bowl) and N facing Magnum. 

Andy Moderow captured this picture of Tincan Proper and Hippy Bowl yesterday in a moment of good light. Note the surface ‘texturing’ and drifting by the winds – a good way to determine likely wind loaded slopes vs. wind scoured.

 

A look at the West face of Magnum from the road in partically obscured light.

 

WIND SLAB:

Today’s main concern are wind slab avalanches. Winds during the past 24-hours have been bumping into the moderate range along the ridgetops from a generally Easterly direction – this is just enough to form wind slabs in favored areas. The pattern will be the same again today. Although travel above treeline may be challenging with low visibility, if you do get to these areas, pay close attention to what the wind has done, or is doing to the snow. With plenty of loose snow to load slopes, it won’t take much to form slabs 1-2′ thick that could be quite touchy if they are fresh. These slabs are likely to be soft and could be lower on slopes where cross loading may have occurred. 

Red Flags to look for:

  1. Recent Avalanches
  2. Cracks that shoot out from your snowmachine, skis or snowboard
  3. A transition from soft snow to stiffer feeling snow when climbing to exposed areas or higher elevations affected by winds
  4. Texturing of the snow surface (may be difficult to see if an inch or two of new snow falls) 

 

Avalanche Problem 2
  • Dry Loose
    Dry Loose
Dry Loose
Dry Loose avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.
More info at Avalanche.org

Expect sluffs to be fast moving today on steep and sustained slopes that have a slick wind-hardened surface underneath. Sluffs will be composed of Friday’s storm snow (8-12″). Cold temperatures yesterday and overnight have likely enhanced the potential for these loose snow avalanches in terrain approaching 40 degrees and more.

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Yes, we are still concerned about glide cracks releasing. Most of the cracks we know about are in areas rarely traveled. The exception is in -1 Bowl (Main Bowl) in the Seattle Creek drainage where glide cracks threaten terrain commonly traveled. Keep an eye out for cracks, which can be difficult with new snow, and limit time underneath them.

Weather
Sun, January 15th, 2017

Yesterday was a break in between storms. Skies were mostly cloudy and snowfall stopped in the early morning – no accumulation in the past 24 hours. Ridgetop winds were light to moderate from a mostly Easterly direction. Temperatures dropped through the day as cold air was pushed in behind the storm system creating some valley fog.  

Today, the second (in a series of two) storm systems is moving in. This event looks to be much like last Friday’s; take a look at the satellite image. Light snowfall has just begun and will continue into tomorrow morning. We should see anywhere from 2-3″ today and 4-6″ tonight (snow to sea level). Will Girdwood get more with this system as with the last? Possible, check back tomorrow morning! Ridgetop winds today are expected to increase to 10-20mph from the East and temperatures warm into the 20’sF at 1,000′ and the mid-teens at the upper elevations.

Martin Luther King day and into the work week, a return to clearing skies, cold temperatures and a breezy Northwest flow is forecast.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 22   0    0 42  
Summit Lake (1400′) 10   0   0 15  
Alyeska Mid (1700′) 18   2   0.2   35  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 17   E   10   25  
Seattle Ridge (2400′) 18   SE   5   15  
Observations
Recent Observations for Turnagain Pass
Date Region Location
12/10/19 Turnagain Avalanche: Tincan and Sunburst from the air
12/10/19 Turnagain Observation: Tincan
12/08/19 Turnagain Avalanche: Tincan
12/06/19 Turnagain Avalanche: Sunburst
12/04/19 Turnagain Observation: Sunburst
12/03/19 Turnagain Observation: Hippy Bowl
12/01/19 Turnagain Observation: Tincan, All elevations
12/01/19 Turnagain Observation: Tincan
11/30/19 Turnagain Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge
11/29/19 Turnagain Observation: Sunburst Ob #2
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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