Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Sat, January 21st, 2017 - 7:00AM
Expires
Sun, January 22nd, 2017 - 7:00AM
Forecaster
Aleph Johnston-Bloom
The Bottom Line

There is a  MODERATE  avalanche danger in the Alpine where triggering a fresh wind slab on leeward terrain is possible and storm slabs could be an issue as the storm progresses throughout the day. If enough snow falls at Treeline and below the LOW  avalanche danger could also rise to MODERATE. Watch for changing conditions and don’t ignore signs of instability like recent avalanches, cracking and collapsing.

*Periphery zones such as Placer, the Girdwood Valley, Johnson Pass and Summit Lake  may have a higher likelihood of triggering a slab avalanche breaking in older weak snow. Approach terrain with a cautious mindset.  Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!

Summit Lake:  Higher snowfall amounts fell on a generally weaker snowpack.  Please check out the Saturday Summit Summary HERE.  

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Sat, January 21st, 2017
Alpine
Above 2,500'
Moderate (2)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
Low (1)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Moderate (2)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
Below Treeline
Below 1,000'
Avalanche risk
Low (1)
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

Yesterday winds were moving snow, a few inches of snow fell overnight and more is in the forecast for today. Winds remain strong enough to load slopes. This wind direction is opposite of the wind event on Thursday so leeward slopes will also be opposite. Fresh wind slabs may form throughout the day and be sensitive to triggering. Steep, unsupported, leeward slopes and ridgeline starting zones will be most suspect. There may also be old stubborn wind slabs from previous loading. Be on the lookout for wind transporting snow and pillowed or drifted areas. Avoid places where the snow feels stiffer and more affected by winds and watch for cracking. 

 

 Wind transport on Seattle Ridge yesterday.

 

Cracking in wind affected snow on Tincan yesterday.

 

Avalanche Problem 2
  • Storm Slabs
    Storm Slabs
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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

The storm is forecasted to continue today but there is still some uncertainty about how much snow will fall and which sections of the avalanche advisory area will be favored. So far the winner is Summit Lake with 9″ overnight.  Center Ridge Snotel has only received 2″ so far but expect the southern end of the Turnagain Pass towards Johnson to have higher snowfall amounts already. Turnagain Pass could receive anywhere from 4″ to over a foot today. If the upper amounts are received there is potential for storm slab avalanches in places where the new snow doesn’t bond to old snow surfaces. In addition to paying attention to new snow amounts watch for temperature changes within the storm. Warmer snow falling on colder snow can quickly make reactive slab conditions. New storm snow will also add to the potential for loose snow avalanches on steep slopes. Paying attention to changing conditions will be crucial today as the avalanche hazard could increase even at lower elevations if this storm produces. 

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 within the snowpack and vary across our region. Following the most recent snowstorm (1/13-1/16) most of the avalanche activity has been observed in the Girdwood Valley. This makes sense since this storm favored this area and left 2-3’ of snow. A handful of small, but deep (to the ground) avalanches were spotted in the alpine this week on Southern aspects of Penguin Ridge, Raggedtop, and Magpie. Summit Lake also had natural avalanches from the Thursday wind event running on weak faceted snow. As more snow falls today remember triggering even a smaller persistent slab could bury a person or take you for a very unfavorable ride over rocks. Pay attention to areas where you can feel weak (sugary) snow under a stiffer snow. If you see recent avalanche activity, experience shooting cracks, or “whumpfing” these are obvious clues that you should avoid steep slopes. 

 

Weather
Sat, January 21st, 2017

Yesterday was mostly cloudy with a few snowflakes falling in the afternoon.  Temperatures were in the high teens to low 20Fs, notably warmer than the previous few days.  Winds were Easterly blowing 15-25 mph gusting into the 30s.  

Overnight a front impacted the area favoring Summit Lake and south. Turnagain received a couple of inches and just inch fell in Girdwood. Snowfall is expected to continue throughout the day will an additional 4-7 inches possible. Winds will be from the SE 5-15 mph with gusts into the 20s. There is some convective potential with this system and overall uncertainty in total snowfall amounts. Temperatures will be in the teens into the mid 20Fs

Tonight snow showers may linger with another 2-4 inches and light E winds. Temperatures will be in the teens. Tomorrow the unsettled weather pattern continues as another system moves towards the region. Stay tuned for snow amounts and temperatures.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′)  16  2 .2   43  
Summit Lake (1400′)  17  9  .9  24
Alyeska Mid (1700′)  18  1  .1  38

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  14  ENE-ESE 15   28  
Seattle Ridge (2400′)  13  SE  22 35  
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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.

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