Turnagain Pass Avalanche Forecast RSS

Archives
ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, January 17th, 2017 - 7:00AM
Expires
Wed, January 18th, 2017 - 7:00AM
Forecaster
Heather Thamm
The Bottom Line

The avalanche danger is MODERATE today in the mountains surrounding Turnagain Pass at all elevations and on all aspects. Loose snow avalanches are likely on steep terrain and could be fast moving and run further than expected. Triggering a soft wind slab 1-2′ thick is possible on steep terrain features and on unsupported slopes that have been loaded by winds. Northern aspects in Turnagain Pass are also suspect of deeper instabilities where a triggering a slab 2+’ thick is also possible.  

***In the Girdwood Valley where 2.5′-3′ of snow fell this weekend, twice as much as Turnagain Pass, heighten avalanche conditions exist. Careful snowpack evaluation, cautious route-finding and conservative decision making are essential today if venturing into this area. It will be important to keep slope angles less than 35 degrees and avoid being under big runout zones. Triggering a slab 3′ thick or deeper is more likely in Girdwood and should warrant extra caution!!!

Thanks to our sponsors!
Tue, January 17th, 2017
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

Storm totals (Jan.13th – Jan.16th) 

  • Turnagain Pass = 15” (1.1” H20)
  • Girdwood = 30” (2.3” H20)
  • Summit Lake = 7” (0.6” H20)

Two snow storms over the weekend brought significant snowfall to our region. Girdwood received about 30” total and Turnagain only 15”.  Moderate Easterly winds occurred during the first storm and blowing snow was observed during the early part of the the second event. Observers over the weekend reported good bonding in the popular areas of Tincan trees and SW shoulder of Sunburst. Due to limited visibility there is not much information from the alpine as to how well this snow has bonded to harder surfaces below. Expect Western (SW – NW aspects) to be more top loaded or cross loaded from the first storm event. Since most of the snowfall arrived yesterday without much wind previous loading patterns may be challenging to indentify. Should winds unexpectedly increase today there is a lot of snow available for transport and fresh wind slabs could be very tender. 

Be on the lookout for obvious clues like recent avalanches, shooting cracks and blowing snow. Evaluate the snow as you travel by jumping/riding over small test slopes and looking for places where the snow feels stiffer and more affected by winds. 

In Girdwood wind slabs may be closer to 3’ thick and could be more tender due to higher snowfall totals and more stress on the snowpack. More caution is advised in this area and it is best to avoid slopes steeper than 35 degrees. 

A photo of the loading patterns on the SW aspect of Tincan Proper from Saturday afternon, Jan.14th, following the first snow storm that left up to 12″ in the upper elevations of Turnagain Pass. Photo by Andy Moderow

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

Yesterday 7” of new snow fell in Turnagain Pass, 13” fell in Girdwood, all without much wind. Snow totals could be deeper in the alpine and triggering a loose snow avalanche will be likely on steeper slopes. Fast moving “sluff” could entrain snow, run further than expected and easily knock you off your feet. Manage this problem by letting the snow move past you and choose terrain that doesn’t have high consequences if you fall. Although it is unlikely to bury a person, keep in mind that larger terrain will have more volume. Cold temperatures could increase this problem today.

 

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

A variety of weak layers exist with in the snowpack and vary across our region. In the heart of our forecast zone,Turnagain Pass, Northern aspects are the most suspect. On the Southern end of Turnagain Pass towards Johnson Pass many aspects have a shallow snowpack, and may harbor more suprises. It will be in these location where triggering a slab on an older layer (facets or buried surface hoar) is possible. In Girdwood where twice as much snow fell and limited snowpack information exists, triggering a deeper more high consequence avalanche is more likely. Should you see recent avalanche activity, experience shooting cracks, or “wumpfing” these are obvious clues that the snowpack is unstable. 

In the lower elevations below 1500’ where a layer of surface hoar was buried by this last storm event, it may be possible to trigger a soft slab on steep unsupported terrain features or along steep gully’s. For today this problem is more of a concern below treeline in places like Portage or Placer Valley. Ice climbers and hikers should be aware of the terrain above, and avoid being in the run-out of large steep slopes. Observers yesterday mentioned that snow drifts near Portage Lake were up to 2’ deep. 

A photo of shooting cracks following a large collapse “wumpf” at about 1800′ an a NE aspect of Raggedtop, Girdwood Valley, following the end of the first storm on Saturday afternoon. 

Weather
Tue, January 17th, 2017

Early yesterday morning snow started falling and by late morning 7 € (17cm) was recorded at the Tincan Beaded Stream station. This snow came in with light NW winds and temperatures were in the low teens F. In Girdwood 13 € of new snow was recorded.  Overnight skies cleared and temperatures dropped to about 0F. Winds have remained light from the West. No precip was recorded overnight.

Today cold arctic air has moved into Southcentral, Alaska and temperatures are expected to remain just below zero today. Winds are forecasted to remain light from the NW and skies are expected to be mostly clear.  

A high pressure system over Interior Alaska is expected to impact Southcentral throughout the week keeping temperatures below zero for next next few days. Skies will be clear, but Northwest winds could pick up tomorrow with ridgetops near 20mph.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 9   1   .1   45  
Summit Lake (1400′) 5   0   0   14  
Alyeska Mid (1700′) 9   3   .26   45  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  2 W   3   10  
Seattle Ridge (2400′) 4    rimed rimed   rimed  
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