Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, February 8th, 2016 - 7:00AM
Expires
Tue, February 9th, 2016 - 7:00AM
Forecaster
Wendy Wagner
The Bottom Line

There is a  MODERATE avalanche danger at the upper elevations around Turnagain Pass for fresh wind slab avalanches. Slab avalanches up to a foot thick will be possible to trigger on slopes that have been, or are being actively, loaded by winds. At the mid-elevations, watch out for glide cracks and stay out from under them; two cracks have released in the past 36-hours. Lastly, give cornices a wide birth; these are large, looming and still breaking off.

*The avalanche danger in Girdwood Valley and Portage Valley may rise to CONSIDERABLE today due to increased precipitation (up to a foot of new snow is possible by this evening).  

Thanks to our sponsors!
Mon, February 8th, 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
  • Wind Slabs
    Wind Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
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.

Likelihood of Avalanches
This graphic depicts how likely you are to trigger avalanches or encounter natural avalanches while traveling on avalanche prone slopes. Unlikely means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. The chance of triggering or observing avalanches increases as we move up the scale. Certain means that humans will be able to trigger avalanches on many slopes, and natural avalanches should be expected.

Size of Avalanches
This graphic depicts the potential size and destructive force of expected avalanches. Small avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become large enough to bury, injure, or kill people, large enough to bury or destroy vehicles and break a few trees, and large enough to destroy railway cars, buildings, or a substantial amount of forest. Historic avalanches are massive events capable of destroying villages and gouging or altering the landscape.
More info at Avalanche.org

After a short break between storms over the weekend, we have another small system over us today that is a bit more ‘blow than snow’. So far only a couple inches of snow has fallen at Turnagain Pass but up to 6″ in the Girdwood Valley; we are expecting another 2-5″ to fall through the day above 1,000′. Ridgetop winds are the big player today and have increased into the strong category from the East. Add these winds to the new snow, and the existing soft snow available for transport, and we have a wind slab avalanche problem. 

If you are headed out today, watch for areas of wind drifted snow and/or slopes that the winds are actively depositing snow. Traveling over wind drifts on gentle slopes and watching for cracks that shoot out from you is a great way to assess if these wind slabs are not bonding well and could avalanche if the slope is steep enough. Quick hand pits in these areas (stiffer snow over softer snow) are good tools as well. 

CORNICES:
Don’t forget, cornices are still falling and the weight of a person and/or snowmachine could help tip the balance. Give these guys a wider berth than you may think necessary along the ridgelines; many have grown to the point where it hard to determine where the ground ends and the cornice begins.

Photo Left: Northeast winds loading Southwest slopes late in the day yesterday, Magnum Ridge. Photo Right: Wind transport over Taylor Pass.
 

Avalanche Problem 2
  • Glide Avalanches
    Glide Avalanches
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
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.

Likelihood of Avalanches
This graphic depicts how likely you are to trigger avalanches or encounter natural avalanches while traveling on avalanche prone slopes. Unlikely means that few avalanches could be triggered in avalanche terrain and natural avalanches are not expected. The chance of triggering or observing avalanches increases as we move up the scale. Certain means that humans will be able to trigger avalanches on many slopes, and natural avalanches should be expected.

Size of Avalanches
This graphic depicts the potential size and destructive force of expected avalanches. Small avalanches are not large enough to bury humans and are relatively harmless unless they carry people over cliffs or through trees or rocks. Moving up the scale, avalanches become large enough to bury, injure, or kill people, large enough to bury or destroy vehicles and break a few trees, and large enough to destroy railway cars, buildings, or a substantial amount of forest. Historic avalanches are massive events capable of destroying villages and gouging or altering the landscape.
More info at Avalanche.org

Two new glide avalanches were seen yesterday in the forecast region. The first was on Pete’s South and the second was in Skookum Valley (side note: if you are not familiar with the names at Turnagain Pass check out this map – maps are found under the resource tab!). Avoiding and limiting time under glide cracks is essential as these avalanches will destroy anything in their path. Many many cracks still litter the mid-elevation band at Turnagain Pass and surrounding regions.

Pete’s South glide avalanche pictured below, before and after the crack released. Photos Tim Glassett. Additional photos can found HERE.
Left, Glide Crack 1:37pm Sat. 2/6                                                Right, Crack released and avalanched sometime before 11:40am Sun. 2/7
 

Skookum glide avalanche, this slide can easily be seen from the Seward Highway as you pass the Portage Valley road.

Additional Concern
  • 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

We have been concerned about a layer of weak older snow that sits roughly 2′ below the surface. This older snow is essentially last week’s surface that became loose and started to facet before it was buried by 2-3′ of storm snow Feb 3-5th. Over the weekend, we have found that this old snow/new snow interface has bonded very well – great news. Report from yesterday’s investigation HERE. However, we have little to no data for areas South of the Pass, such as the high elevations above the Johnson Pass trail or Summit Lake. Hence, there may be areas that did not bond well and if this is the case large and ‘connected’ avalanches will be possible. 

Weather
Mon, February 8th, 2016

Partly cloudy skies and light winds covered the region yesterday morning. By the early afternoon, a weak low-pressure system began to move in bringing cloud cover and a bump in Easterly winds (~25mph averages) along the ridgetops. Temperatures remained mild in the 20’sF at the mid-elevations.

Overnight, we have seen an inch of new snow at Turnagain Pass with up to 6″ in the Girdwood Valley. The rain/snow line is currently ~500′ and may  rise to 1,000′ by later today. We are expecting an additional 2-5″ at the higher elevations by 6pm. Winds will continue in the 20-30mph range from the East along the ridgetops and temperatures are expected to rise to the mid 30’s at 1,000′ and the mid 20’s at 3,500′.  

Tuesday looks to be a short break in weather before a much warmer and wetter system moves in from the South for Wednesday. We could see rain above 2,000′ with this next round of storms mid-week.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 28   1   0.1   109  
Summit Lake (1400′) 29   0   0   32  
Alyeska Mid (1700′) 30   6    0.5 87  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 22   NE    22 53  
Seattle Ridge (2400′) 24   –   –   –  
Observations
Recent Observations for Turnagain Pass
Date Region Location
12/06/19 Turnagain Avalanche: Sunburst
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
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