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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, March 23rd, 2016 - 7:00AM
Expires
Thu, March 24th, 2016 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

The avalanche danger is CONSIDERABLE  above 1,000′ today.  Human triggered wet loose and wet slab avalanches in steep terrain (greater than 35 degrees) will be likely and large enough to be dangerous as the moist surface snow extends up to ridgetops in many locations around Turnagain Pass. Natural wet avalanches will be possible.  Cautious terrain evaluation is essential today.

In addition, it will be possible to trigger a tender wind slab and/or cornice fall in the Alpine. In the mid-elevation band, the already active glide avalanche cycle seems to be ramping up. New glide cracks are appearing, growing and releasing very large avalanches in the past two days. Avoid travel underneath glide cracks.

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Wed, March 23rd, 2016
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Considerable (3)
Treeline
1,000'-2,500'
Avalanche risk
Considerable (3)
Below Treeline
Below 1,000'
Avalanche risk
No Rating (0)
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

For the third night in a row temperatures stayed above freezing in the low to mid elevations and over 1.5″ of rain fell on the snowpack in the last 24 hrs up to 2000′ or higher at Turnagain Pass. Natural wet loose avalanches were observed yesterday and were large enough to injure or bury a person. Triggering a wet loose or a wet slab avalanche in this saturated snow will be likely today and may be occurring naturally as well. Wet avalanches once initiated can entrain more snow rapidly and are very hard to get out of. They can be particularly hazardous if they push you into a terrain trap and bury you deeply. Stick to low angle terrain and avoid runout zones where avalanches from above may catch you. Warm temperatures and rain showers are forecasted to continue today. There may also be some sunshine that could exacerbate the wet snow issues. Ski and snowmachine conditions will not be pleasant.

 

Turnagain Pass weather at 2:30 pm yesterday.

Avalanche Problem 2
  • 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

We have been talking about glide cracks and glide avalanches for months and the past couple weeks have been notably active. The past couple days maybe even more so as the snowpack gets wetter and more slurpy like. New cracks are appearing and releasing as very large glide avalanches. The idea of someone getting caught in one of these is pretty terrifying. Navigating through the mid-elevation band is getting more and more complex. There is a glide crack that is opening directly above the Seattle Ridge up-track. I couldn’t get a good picture of it yesterday but I don’t want to be parked or stuck under that and traveling under a glide crack is a total dice roll. The only way to mange this hazard is avoidance. 

 

Glide avalanche above the Bertha Creek parking lot.

 Debris pile from the avalanche above.

 Whiteline avalanche path glide crack to glide avalanche progression over 3 days. Images from 3.20, 3.21 and 3.22. Photos: Tim Glassett

Additional Concern
  • 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

Wind slabs and Cornices:

Yesterday in the Alpine the precipitation was falling as snow and there were sustained easterly winds in the 20-30s with gusts into the 50s. This may have created tender wind slabs in ridgeline starting zones and added weight to already very large cornices. The wind slabs will be found in steep leeward terrain. Watch for cracking in wind-loaded areas and avoid travel on or under cornices. Warm temperatures can make cornices more likely to fail. 

Weather
Wed, March 23rd, 2016

Yesterday was overcast with broken clouds and rain/snow showers on and off throughout the day. Temperatures were above freezing at lower elevations and in the high 20Fs at 3000′ and stayed warm overnight. Winds were easterly, 20-30 mph with gusts into the 50s.  

Today will be partly to mostly cloudy with isolated showers and light winds. Temperatures are forecasted to be in the 40Fs at 1000′ and the mid to high 30Fs at 3000′.

Tomorrow may see a bit of clearing however the unsettled pattern with cloudy skies and showers persists throughout the week with more moisture on tap for the weekend.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 36    rain 1.7   129  
Summit Lake (1400′) 37    drizzle .1    43
Alyeska Mid (1700′)  35 rain   1.1    107

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 28   ENE   27   52  
Seattle Ridge (2400′) 30   SE    25 52  
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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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