Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, December 9th, 2017 - 7:00AM
Expires
Sun, December 10th, 2017 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

The avalanche danger is  CONSIDERABLE on all aspects and elevations above 1500′. Recent storms have loaded a weak snowpack.  Triggering a slab 2-4+ feet could release on slopes steeper than 30 degrees and remote triggered avalanches are possible. Cautious route-finding, conservative decision-making are essential today.    

Below 1000′, where little snow exists, the avalanche danger is MODERATE where an avalanche could run into steep channeled terrain.  

**Summit Lake weekly Summary can be found HERE.

Thanks to our sponsors!
Sat, December 9th, 2017
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
Moderate (2)
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
Moderate (2)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

Yesterday’s benign weather and patches of clear skies allowed for a good look around Turnagain Pass to inventory the results of Thursday’s storm. Evidence of some natural avalanche activity could be seen in steep channeled terrain, but many slopes still remain intact. Incremental loading from multiple storms over the last two weeks has buried a reactive layer of weak faceted snow near the ground. Facets have been found above and below a melt/freeze crust near the ground that is acting as a slick bed surface. This poor structure appears to be widespread both in the middle and upper elevations throughout Turnagain Pass and Girdwood. Last week when the slab was thinner observers reported “whumpfing” sounds on a daily basis including a very loud collapse that remote triggered two avalanches on Tincan, one on each side CFR ridge. Today triggering a large propagating avalanche is likely in avalanche terrain, especially in places where the snow pack is thinner and easier to penetrate the weak layer.  Keep in mind that the Northern end of Turnagain Pass has seen heavier precipitation and higher snow totals in the alpine compared to the Southern end of Turnagain Pass. This means that triggering an avalanche may be easier in places like Sunburst, Magnum or Cornbiscuit that have less snow. Triggering an avalanche could propagate an entire slope releasing to the ground and running the entire slide path. The big take home message is dangerous avalanche conditions exist and there is limited info beyond Tincan. Remember this is not an avalanche problem that can be out smarted or easily managed. Avoiding all runout zones and avalanche terrain steeper than 30 degrees is essential today.  

 

A test pit at 3100′ yesterday revealed weak faceted snow below and above melt/freeze crusts formed in October. 

 

Debris at the bottom of steep channeled terrain on the North side of Tincan. New debris was also seen in Todd’s run that wasn’t there before the Thursday storm. 

 

An avalanche seen yesterday that likely released mid to late storm on Cornbiscuit Thursday. Cornbiscuit is a good example of where the snow pack is thinner and could be easier to trigger a persistent slab. 

 

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

Strong Easterly winds this week have loaded leeward aspects, cross loaded many gullies and loaded corniced ridges. Human triggered wind slab avalanches or cornice falls are likely, but what is more of a concern is the potential for one of these to trigger a much larger and dangerous persistent slab avalanche as discussed above.  AGAIN today is not the day to be pushing into avalanche terrain! 

Additional Concern
  • 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

Yesterday clear skies allowed for a superficial surface crust to form to 2500’. Today as temperatures rise above freezing at ridgetops and clouds move overhead, expect this crust to start breaking down. Wet loose avalanches could occur later in the afternoon with the arrival of rain showers. Pay attention to snow conditions becoming wet and avoid terrain traps or steep terrain features. Don’t forget above freezing temperatures is a red flag warning to avoid avalanche terrain.

Weather
Sat, December 9th, 2017

Yesterday skis were broken with patches of blue sky in the afternoon and evening in Turnagain Pass. Temperatures remained above freezing at 1000′ and averaged 28F near ridgetops. Overnight temperatures have been on a steady incline and have reached 30F at Sunburst Wx Station (3800′) and 34F at Seattle Ridge Wx Station (2400′). No new precipitation was recorded in Turnagain Pass. Winds were light from the East 5-15mph yesterday and have increased to 15-30mph from East this morning.  

Today temperatures are expected to remain above freezing even in the upper elevations. Scattered rain showers are possible today with 0.16 € of rain that could reach 3000′. Easterly ridge top winds 10-30mph are expected to increase into the 40s this evening. Unusually warm air will remain in the upper elevations and precipitation is expected to increase early this evening with a potential for 0.5 € of rain tonight.    

Warm, wet and windy weather pattern is expected throughout the week as a series of low pressure systems continue to impact our region. Sunday evening through Monday, another strong storm is on tap and should bring strong winds, above freezing temps and a mix of rain and snow in the upper elevations.  

*Center Ridge SNOTEL is reporting erroneous temperature data. See  Turnagain Pass DOT weather station  for accurate temperature at 1000′.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) *36   0   0   26  
Summit Lake (1400′) 30   0   0   10  
Alyeska Mid (1700′) 34   trace   0.05   19  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 28   ENE   9   30  
Seattle Ridge (2400′) 31   SE   13   27  
Observations
Recent Observations for Turnagain Pass
Date Region Location
12/04/19 Turnagain Observation: Sunburst
12/03/19 Turnagain Observation: HIppy Bowl
12/01/19 Turnagain Observation: Tincan, All elevations
12/01/19 Turnagain Observation: Tincan
11/30/19 Turnagain Observation: Tincan Treeline Plateau/ Common Bowl/ Ridge
11/29/19 Turnagain Observation: Sunburst Ob #2
11/29/19 Turnagain Observation: Sunburst Ob #1
11/27/19 Turnagain Observation: Tincan
11/25/19 Turnagain Observation: Sunnyside
11/18/19 Turnagain Observation: Turnagain Pass – Road obs
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.

Subscribe to Turnagain Pass
Avalanche Forecast by Email