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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, March 22nd, 2016 - 7:00AM
Expires
Wed, March 23rd, 2016 - 7:00AM
Forecaster
Graham Predeger
The Bottom Line

The avalanche danger is MODERATE above 1,000′ today.   Wet loose avalanches in steep terrain (greater than 35 degrees) will be possible to trigger and are producing enough mass to be problematic as the moist surface extends up to ridgetops in many locations around Turnagain Pass.   Cautious terrain evaluation is essential today in order to avoid being pushed into a terrain trap by wet, heavy moving snow.

Winds are unlikely to effect yesterday’s moist surface but any new snow and wind today will build in to shallow, but tender wind slabs in the alpine.   Cracks and cornices continue to warrant mention as well.   At least three new glide avalanches were observed yesterday, post-storm.

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Tue, March 22nd, 2016
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
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
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

Observations from the field yesterday found a moist surface up to at least 3200’ in the wake of the Sunday/ Monday warm up.  Unfortunately this wasn’t only relegated to solar aspects but shadier north aspects were harboring a moist surface as well.  The weekend storm snow is settling out rather rapidly, compressing the several inches of cooler, low-density snow (from Saturday morning) into a thin weak layer 6-16” below the surface.  In steep terrain, wet-loose snow yesterday was easy to initiate, building enough mass and momentum that it could pose a problem for a skier in consequential terrain.  These are relatively small but heavy and powerful avalanches that are difficult to escape from.  Keep this in mind as you are travelling above any terrain traps such as gullies, trees, cliffs or glide cracks.  Snowmachiners: The surface is such right now that you can entrain a significant amount of heavy wet snow as you descend.  It’ll be prudent to ‘manage’ this heavy sluff and avoid terrain traps. 

Last night was the second night in a row where temperatures did not freeze overnight below about 2,000’ making for a punchy, rotten snowpack.  If temperatures do spike again today in the afternoon or we receive significant rain on snow, it’s entirely possible that wet loose avalanches could pull out dangerous wet slabs in this mid-elevation band.

Wet loose avalanches skiers-right of Todd’s run.  Eddies glide crack-complex in the background.

 

Roller balls are another good clue to a warming surface, primed for wet-loose avalanches.  

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

Good visibility allowed us a look around yesterday to add to a growing list of glide avalanches across the region.  The post-storm tally was 3 new glides: Penguin ridge, Skookum Valley and Seattle ridge (N. of uptrack).  As long as glide cracks continue to open up, move and release, we will stress the importance of avoiding them, which is THE ONLY WAY TO MANAGE THIS AVALANCHE PROBLEM.  Remember, this is the entire winters snowpack releasing to the ground suddenly and without warning.  Simple avoidance of glide cracks continues to be the key.

CORNICES:  We did see some active cornice shedding during the heat of the day yesterday.  Take extra precautions when travelling around cornices as they tend to break much further back on ridges than often times expected.

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

Winds have been cranking enough in the alpine to transport any available snow into shallow wind slabs.  Likely these will be found somewhere above 3500’ today where the snow surface dries out.  2-4” of new snow forecasted and moderate easterly winds in the upper elevations today will add to existing wind slabs in the 1-2’ range.

Weather
Tue, March 22nd, 2016

The most notable aspect to yesterday’s weather was the warmth in the air.   40-degree temps are finally acting to melt out some of the SUV-swallowing potholes in the motorized lot at 1,000′.   Pavement is again visible!   Ridgetop temperatures spiked at 34 degrees in the afternoon on the top of Sunburst (3800′).   Just a trace of precip was measured yesterday morning before skies broke mostly sunny.   Winds were light (gusting into the 20’s) from the East before picking up overnight.

Today we can expect up to another half inch of water throughout the day with a rain/ snow line around 2,000′.   Winds will be from the east in the 20-30 mph range.   Temperatures will again be unseasonably warm in the high 30’s to low 40’s at 1,000′.

The well-developed low tracking North into the Gulf today may not influence us much tomorrow as a persistent upper level ridge looks to limit its advance onto the mainland.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 39 0   .2   131  
Summit Lake (1400′)  39 0   .3    45
Alyeska Mid (1700′)  37  0  n/a 109  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  30  ENE 17    49
Seattle Ridge (2400′)  33  SE 18   39  
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Riding Areas
Updated Mon, December 02nd, 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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