Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, March 17th, 2018 - 7:00AM
Expires
Sun, March 18th, 2018 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

The avalanche danger is CONSIDERABLE on all aspects and elevations, and may increase to HIGH in the afternoon if we see natural avalanches on Southerly aspects. Triggering a slab avalanche 2-4+’ thick is likely on all aspects below 3000′. Above this elevation where slab depths are deeper, the potential for triggering a very deep and dangerous avalanche exists. Be aware of newly formed wind slabs and unstable cornices in the alpine. Pay attention to daily warming and changing snow conditions and if you see natural avalanches avoid all avalanche terrain. Cautious route-finding and conservative decision making are essential.  

Dangerous avalanche conditions also exist in Summit Lake, check out the most recent  Summit snowpack and avalanche summary if you are headed South of Turnagian Pass.

Thanks to our sponsors!
Sat, March 17th, 2018
Alpine
Above 2,500'
Considerable (3)
Avalanche risk
Treeline
1,000'-2,500'
Considerable (3)
Avalanche risk
Below Treeline
Below 1,000'
Considerable (3)
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
Considerable (3)
Danger Scale:
No Rating (0)
Low (1)
Moderate (2)
Considerable (3)
High (4)
Extreme (5)
Avalanche Problem 1
  • Deep Persistent Slabs
    Deep Persistent Slabs
  • Almost Certain
    Very Likely
    Likely
    Possible
    Unlikely
    Likelihood
  • Historic
    Very Large
    Large
    Small
    Size
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and 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

Avalanche danger will rise as a superficial melt-freeze crust breaks down with daily warming and radiation from the sun this afternoon. Light rain fell yesterday, and last night was the second night in a row with above freezing temps in the lower elevations.  Large human triggered avalanches and/or natural avalanches have released daily since Monday from Seward all the way to Girdwood. Some of these avalanches have been remotely triggered while others have released after a skier or snowmachiner were well onto a slope. So far we’ve seen one ‘very large’ natural avalanche, where the crown was a mile-wide, on a NE aspect of Skookum Valley near Placer.  Most of these avalanches have occurred below 3000’, releasing on weak faceted snow on a slick crust, 2-4 feet below the surface. Widespread buried surface hoar and facets have been well documented at all elevations and this poor snowpack structure leaves us concerned about the potential of another very large high-consequence avalanche. A lot of uncertainty remains in the Alpine where slab depths are much deeper and triggering an avalanche could be more stubborn. Today as surfaces become moist and crusts start to break down with daily warming, keep your terrain choices mellow. Slope angles steeper than 30 degrees, and smaller unsupported terrain features are all suspect. There is potential to trigger a slab remotely from below a slope or along a ridge. If you’re playing in the flats, be aware of other parties in the area and avoid runout zones. 

Video of this week’s avalanche cycle in the Kenai Mountains.  

 

A natural avalanche seen on SE aspect of Seattle Ridge yesterday afternoon. 

 

Large natural avalanche that released on Tuesday afternoon on a NE aspect of Skookum Valley near Placer. 

 

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

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

Wet loose avalanches or roller balls today are indicative of solar radiation and/ or daily warming temperatures affecting change on the snowpack. We have been seeing this throughout the week with unusually warm temperatures. A wet point release could be small to large and has the potential to trigger a much larger, more dangerous slab, particularly on steep southerly aspects. If the sun comes out this afternoon and evening, natural wet loose avalanches are expected. Pay attention to the surface crust as it breaks down and becomes moist. This will be your first clue that the avalanche danger is increasing.

Small wet point release avalanches were seen yesterday below 2000′ on all aspects in very steep terrain where light rain was falling to this elevation. Today expect these to be more prominent on Southerly aspects at all elevations. 

Additional Concern
  • 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 Slabs: In the upper elevations Easterly winds 20-45mph yesterday were loading leeward slopes and adding stress to a very stressed out snowpack. Triggering a newly formed wind slab up to a foot deep is likely on leeward features in the upper elevations where dry-loose snow was available for transport. Sun and warm temperatures could make wind slabs easier to trigger. A fresh wind slab could step down to older snow in the snowpack and create a much deeper and more dangerous avalanche. 

Cornice Fall: Cornices have grown significantly since the March 9th storm, an event that arrived with strong winds and dumped 3-4’ of new snow. If the sun appears it will be heating up cornices today and could make them more unstable. Give corniced ridges an extra wide berth and minimize time spent below them. A cornice fall could trigger and propagate an avalanche on a slope below.

Weather
Sat, March 17th, 2018

 Yesterday was overcast with scattered rain showers below 2000′. Only a trace of precipitation was recorded. Daytime temps reached the mid 40F’s near sea level and mid 30F’s in the mid elevations. Temperatures in the alpine were in the upper 20F’s. Temperatures remained at or above freezing for the second night in a row below 1500′.    Easterly ridge top winds 15-45mph gradually decreased in the late afternoon and evening.      

Today expect scattered rain showers in the morning with clearing skies in the afternoon. Clouds will move back into the area this evening. Unusually warm temperatures will continue today with highs in the mid 40F’s at sea level and mid 30F’s in the alpine. Overnight temps will dip into the upper-20F’s to low-30F’s. Winds will be light from the South.  

Temperatures are expected to remain warm through Sunday and into Monday as another front moves through Southcentral, AK. The Southwest direction of this low will likely favor Cook Inlet and the Mat-Su Valley for precipitation, a mix of rain and snow. Cooler temperatures associated with Arctic air moving into our region are in the forecast by mid week.    

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 35 0   .1   85  
Summit Lake (1400′) 35   0   0   32  
Alyeska Mid (1700′) 33   0    .07 79  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24   ENE   10 50  
Seattle Ridge (2400′) 29   ESE   14   44  
Observations
Recent Observations for Turnagain Pass
Date Region Location
12/10/19 Turnagain Avalanche: Tincan and Sunburst from the air
12/10/19 Turnagain Observation: Tincan
12/08/19 Turnagain Avalanche: Tincan
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
Riding Areas
Updated Wed, December 11th, 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