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Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sun, December 7th, 2014 - 7:00AM
Expires
Mon, December 8th, 2014 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

The avalanche danger will rise to MODERATE today at all elevations above 1,500′. Below 1,500′, little to no snow cover results in No Rating. Wet snow avalanches will be possible to trigger near treeline in areas with rain falling on snow. These wet avalanches are expected to be heavy and dense sluffs that can be initiated on slopes over 35 degrees and on all aspects. At elevations above treeline, where 6-10″ of snow is expected to fall, wind slab avalanches will be the main concern due to strong winds loading leeward slopes.

*The avalanche danger may rise to CONSIDERABLE in areas seeing significant precipitation (over an inch of rain through the day). These areas are on the periphery of the forecast zone, such as Portage Valley and Whittier.

——————————————————————–

The next advisory will be Tuesday Dec 9th at 7am.

Avalanche Outlook for Monday: Expect similar avalanche conditions for Monday. With continued rain to treeline a MODERATE danger for wet avalanches is likely to remain at the treeline elevation. Above treeline, another 3-5″ of snow is expected with moderate to strong winds which will keep wind slab avalanches a concern.

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Sun, December 7th, 2014
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

It is the dreaded rain-on-snow that is in our future today, and into the early part of the week. With climbing temperatures overnight and periods of heavy rain expected at sea level, the question is, “How high will the rain get?” The answer is, 1,200′ for sure, likely 1,500′ at times and possibly a bit higher. 

Wet loose snow avalanches will be the most likely type of wet avalanche to be triggered. These can entrain significant amounts of heavy dense snow if the slope is sustained and steep enough (> 35 degrees). If you are getting out today, watch for areas where the snow is becoming saturated and heavy. Steering clear of steep saturated slopes will be good ways to avoid a wet sluff. Also, keep in mind terrain traps, such as steep narrow gullies in the Tincan Trees. These steep walled and narrow terrain features can pose a threat if even a small amount of heavy snow slides down onto you.

Avalanche Problem 2
  • 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

In the Alpine terrain, above treeline, we are expecting around 6-10″ of wet to moist snow to fall. Along with this, winds are forecast to be strong from the East and Northeast which will quickly form wind slabs, drifts and cornices. The warm nature of the new snow will allow it to bond rather quickly to the preexisting surface, however with the rapid loading expected today, be wary of fresh slabs and drifts. Watching for current wind loading and cracks shooting from your skis/board will be good ways to suss out if slabs are sensitive.

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

It is time to put glide avalanches back on our radar. With warming temperatures we could see a number of glides cracks open up and release in the next several days. Yesterday, we saw a slab that has moved during the past week and looks ready to avalanche. Staying out from under glide cracks will be key this week.

Glide slab in the Seattle Creek drainage (East facing ~2,000′). 

Weather
Sun, December 7th, 2014

Weather yesterday was relatively mild with overcast skies, light winds from the East and Northeast and only a trace to an inch of snow accumulating above 1,000′ (rain below).  

Overnight, temperatures and winds have increased at all elevations as the leading edge of a large and complex low pressure system moves in from the Gulf. We can expect up to an inch of rain to fall throughout the day below 1,500′ with 6-10″ of wet snow above. Winds have already begun to climb and will be blowing from the East in the 35-45mph range. Temperatures are also climbing and should top out around 30 deg. F on the ridgetops and the upper 30’sF at 1,000′ on Turnagain Pass.

For Monday, precipitation intensity will diminish slightly with forecast amounts around .5″ of rain and 3-5″ of snow (rain/snow line ~1,200′). Winds will continue from the East and should diminish slightly as well. Temperatures will remain warm, near 30F on the ridgetops and the upper 30’s at 1,000′.  It looks as though it will be Wednesday before temperatures cool back off for snow to make it down near sea level.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 34   1   0.1   20  
Summit Lake (1400′) 33   0   0    5
Alyeska Mid (1700′) 33   1   0.22   17  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 29   E   16   55  
Seattle Ridge (2400′) 29   NE   18 46  
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Riding Areas
Updated Mon, October 26th, 2020

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
Placer River
Closed
Skookum Drainage
Closed
Turnagain Pass
Closed
Twentymile
Closed
Seward District
Carter Lake
Closed
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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.