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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sun, April 10th, 2016 - 7:00AM
Expires
Mon, April 11th, 2016 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

There is a CONSIDERABLE avalanche danger in the backcountry for glide avalanches, wet snow avalanches and storm snow avalanches. Glide cracks continue to release on all aspects under 3,000′. Travel under glide cracks is NOT recommended. At elevations below 2,500′, human triggered wet snow avalanches are likely where rain is saturating the snowpack. And last, at elevations above 3,000′, naturally occurring wind slab avalanches 1-2′ thick are possible.  

If you are headed into the mountains today, expert level terrain management and observation skills are key to steer clear of glide cracks, steep slopes with saturated snow and slopes with recent storm snow.

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Sun, April 10th, 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
  • 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

As a warm band of moisture moves through the region we contine to see rain between 2,000′ and 2,500′ and wet snow above this. So far total rainfall during the storm (beginning early yesterday morning) is around 1 to 2″ in the Girdwood and Portage Valley areas – lesser amounts have been seen on Turnagain Pass and South. We have another .5-.75″ of rain on the way today with snow up high. 

Although we are seeing a storm moving through, the main concern will remain focused on glide avalanches. Two new glide cracks released yesterday in the Turnagain Pass region. One (pictured below) was on the South side of Seattle Ridge and the other was on the North face of Sharks Fin. The fact these cracks keep releasing into avalanches should be evidence enough that avoiding travel under glide cracks remains a prudent rule. 

Glide avalanche from yesterday on Seattle Ridge (South end across from the Bertha Creek campground)

 

Keeping an eye on the Seattle Ridge ‘up-track’. The last glide avalanche threathening this popular zone was on Thursday, April 7th.

Avalanche Problem 2
  • 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

As rain continues to melt and saturate the snowpack from 2,500′ and below, wet loose snow avalanches are a concern. At these elevations, triggering wet snow sluffs on steep slopes is likely – if one were to travel on steep slopes in this weather. At the elevation band between 2,500 and 3,000′ where wet snow is falling, shallow wet sluffs composed of the new snow are likely to occur naturally. We have not seen the typical springtime large wet avalanches that are compose of the older snow yet, but are watching for this.

Saturated and mostly unsupportable snow exists at the lower and mid-elevations along Turnagain Pass. This photo is near the Sunburst parking lot at 900′ in elevation.

 

Rain and warm weather is melting the snow out quickly along the South end of Turnagain Pass. Photo is of the Sunburst parking lot looking West toward Seattle Ridge.

Additional Concern
  • 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

At elevations high enough to see dry(ish) snow, storm snow instabilities will be seen. At what elevations will this be? Likely above 3,000′ and in the upper sections of the starting zones along Turnagain Pass. As of this morning there could be anywhere between 6-16+” of snow that has fallen, the most in areas close to Turnagain Arm (Between Girdwood and Tincan). We are looking at another 3-7″ today. With the high winds at these upper elevations, wind slabs 1-2′ thick are likely and could release naturally. Cornice falls are also an issue. both these types of avalanches could entrain wet snow on the way down and run quite far in steep channeled terrain.

Weather
Sun, April 10th, 2016

A strong frontal system moving through the region has brought rain, up to 2,500, beginning early yesterday morning. Heavy rain fell in Girdwood and as far South as Tincan but only light rain was seen South of the Pass, from Sunburst and on. Ridgetop winds over the past 24-hours have been strong out of the East, averaging ~40mph with gusts to the 70’s. Temperatures are warm, mid 20’s at 4,000′ and reaching the upper 30’sF at 1,000′.  

Today the storm system will continue to push through and exit the area by Monday. We should pick up another .5-.75″ of rain up to 2,500′ (possibly higher) with 4-7″ of wet snow above this. Ridgetop winds are slated to remain strong in the 30-40mph range from the East. Temperatures should stay warm with highs today around 40F at 1,000′ and up to 30F on the ridgetops. Both precipitation and wind should decrease overnight tonight and temperatures cool off.

For Monday and Tuesday, a colder low pressure system moves past to our South that may push snow/rain and wind our way. If this low is South enough in the Gulf we could see relatively nice skies, stay tuned on tomorrow’s forecast.

*The Center Ridge SNOTEL is not reporting accurate precipitaiton data. Also, the RWIS Turnagain Pass station is down. Precipitation numbers for Turnagain Pass are estimated at ~1″ of water during this storm (past 30 hours).

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 36   not reporting   0.3* (under reporting) 114  
Summit Lake (1400′) 39   0   0   33  
Alyeska Mid (1700′) 35   rain   0.7   101  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 27   NE   41   75  
Seattle Ridge (2400′) 28   SE   28   56  
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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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