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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 15th, 2013 - 7:00AM
Expires
Mon, December 16th, 2013 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

With 2 days of new snow and wind, we have a  MODERATE  avalanche danger for wind slab and loose snow avalanches. Wind slabs 1-2+’ deep will be possible for a person to trigger on upper elevation slopes over 35 degrees. Watch for any area where the wind has blown the new snow into drifts and slabs €“ most likely just off ridgelines and rollovers. Otherwise, sluffing in the new light snow should be expected.

*Check out the storm totals below in the Mountain Weather section.

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Sun, December 15th, 2013
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Moderate (2)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
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
Moderate (2)
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

Wind slab avalanches will be the most concerning avalanche problem today. With storm totals upwards of 15-18″ these are expected to be 1-2+’ deep, soft and potentially quite sensitive to human triggers. They are most likely to be found on slopes over 35 degrees just off ridgelines, on rollovers and the side-walls of gullies. Keep an eye out for any slope with signs of recent wind loading – this means areas with stiffer snow over weaker snow, smooth rounded surfaces and hollow feeling snow.

Though the wind died down in most locations yesterday afternoon, it was blowing moderately to strong from the east early in the day yesterday. Though any natural activity has likely ceased, I’m expecting there are some good sized wind slabs that are still fresh enough to cause problems for people. If the visibility breaks enough for travel to the more exposed terrain, finding a 2’ deep unmanageable wind slab is not out of the question.


Below is a poor image of a few small wind slab avalanches on Tincan yesterday (human triggered 2,500′, W aspect). It is still uncertain how the upper elevation wind affected slopes are handling this new load. More on yesterday HERE and HERE.

How is the early December crust behaving?
The new snow did fall on a ~¼” breakable crust which had, in places, surface hoar on top. Though this interface was showing a fairly good bond yesterday, I would not count out that avalanches could be larger and run further with this crust providing a slippery bed surface and the added uncertainty of the now buried surface hoar.

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

It will be mostly a sluff management day. With decreasing temperature and generally calm to light winds, much of the new snow will be in a very loose unconsolidated state (‘cold smoke’?) and initiating a loose snow avalanche will be likely. In continuously steep, channeled terrain expect sluffs to gain in volume, run fairly far and become more of a concern.

Weather
Sun, December 15th, 2013

24-hour snowfall totals (6am Saturday to 6am Sunday):

  • Turnagain Pass SNOTEL: 9 € (0.5 € water equivalent, 5.5% density-dang…)
  • Summit Creek SNOTEL: 3 €   (0.2 € water eq., 6.67%)
  • Girdwood Valley: ~6 € (0.4 € water eq., 6.7%) *not all Girdwood Valley stations reporting – rough estimate.

 Storm totals are (8am Friday to 6am Sunday €“ past 46 hours):

  • Turnagain Pass: 17 €  (1 € water equivalent, 5.9% density)
  • Summit Creek SNOTEL: 8 €    (0.5 water eq., 6.25%)
  • Girdwood Valley: ~15 €    (~1 € water eq., 6.7%)

Currently, light snowfall continues in the Eastern Turnagain Arm which may add another inch this morning. The easterly wind that averaged 20-30mph with gusts to the 50’s yesterday morning has decreased to the 5-10mph range and backed to the north. Temperature has dropped from the 20’s to the single digits overnight.

Today, skies should slowly break and snow showers taper off as the low pressure over us heads east and colder drier air moves in. Wind looks to remain light, 5mph, from the north and temperature remain in the single digits to low teens at most locations.

Tomorrow and Tuesday look to be clear and cold before another system moves in Wednesday/Thursday. It looks like winter is arriving!

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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
Lost Lake Trail
Closed
Primrose Trail
Closed
Resurrection Pass Trail
Closed
Snug Harbor
Closed
South Fork Snow River Corridor
Closed
Summit Lake
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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.