Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Wed, December 16th, 2015 - 7:00AM
Expires
Thu, December 17th, 2015 - 7:00AM
Forecaster
Heather Thamm
Avalanche risk The Bottom Line

Today the avalanche danger is MODERATE where loose snow avalanches and tender wind slabs could have high consequences on steep and exposed terrain features.  Wind slabs 8-10″ thick will be more likely in the Alpine where poor visibility could make assessing the conditions difficult today.    Assess changing surface conditions and be on the look out for loading snow and shooting cracks.

Ice climbers: Snowfall totals in Portage Valley have been verified at 12 € or more on Monday and another 3-5″ fell yesterday.   This is potentially more than a   €œmoderate €  avalanche problem for this user group given the extreme and complex nature of the terrain.  

Special Announcements

Fireside Chat #3 €“ Human factors and decision-making on Thursday, Dec 17th!!  Join our newest CNFAIC forecaster, Aleph Johnston-Bloom Thursday night from  6:30-8:00pm in Girdwood at the Glacier Ranger Station (Forest Service office)  for an introduction to what avalanche professionals and psychologists refer to as the €œhuman factor € as it relates to decision-making in the backcountry

CNFAIC is hosting a Free Avalanche Rescue Workshop on Sunday, December 20th at Turnagain Pass. This is a great opportunity to practice beacon searches, learn strategic shoveling techniques and meet local forecasters! This workshop is open to everyone and anyone, novices and experts.

More areas are open for over snow vehicles on the Seward Ranger District!  Please see updated table at the bottom of this page.

Thanks to our sponsors!
Wed, December 16th, 2015
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
  • 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

Yesterday snowfall was concentrated near Turnigain Arm favoring the Northern side Turnagain Pass and Portage Valley with a total of 3-5” of new snow. Moderate ridgetop winds flipped from the Northeast to a Westerly direction for several hours during the most intense burst of snow flurries. Today another small shot of snow is expected along with moderate winds from the Northeast. Loose snow avalanches and tender wind slabs up to 8-10” thick are possible on steep convex terrain features and just below ridgelines, on all aspects.  This unstable snow could have high consequences if triggered on exposed terrain features like cliffs, gullies, and large open slopes.

A total of 2-3’ of new snow has fallen since last Wednesday and has left a mostly right side up snow pack. Many layers of new snow exist as a result of incremental loading and moderate winds in the upper elevations. Visibility is expected to be limited today, but if a window opens up, assess snow conditions carefully at higher elevations. 

Snow flurries intensified yesterday in the early afternoon making visibility difficult at Sunburst. 

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 actively tracking several layers of weak snow buried under 2-3’ of new snow over the past week. Data collected over the last 3 days (including heavy impact from motorized slope testers) is pointing towards good stability. Right now this problem is becoming an outlier, but we will continue to monitor these layers with any additional loading or stress to the snowpack. 

Weather
Wed, December 16th, 2015

Yesterday snow showers intensified for several hours as a cold front left 3-5 € of snow in the upper elevations of Turnagain Pass and Portage Valley. Ridgetop winds were moderate from the Northeast, switching to a Westerly pattern in the afternoon through late evening. Temps were cool, high teens F in the alpine, and high 20F’s at sea level.  Overnight winds were light from the Northeast.

Today expect more showery conditions with another 3-5 € of new snow in upper elevations. Easterly ridgetop winds will increase to 15-30mph this morning and remain moderate into the evening.

Tomorrow more snow showers are anticipated. Temps are expected to increase to freezing 32F at sea level causing mixed rain and snow. Winds are expected to be light to moderate from the East.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 24F   3   0.3   39  
Summit Lake (1400′) 19F    1 0.1   15  
Alyeska Mid (1700′) 25F   2    0.2 33  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 17F   Var.   12    54
Seattle Ridge (2400′) 19F   n/a    n/a   n/a    
Observations
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Riding Areas
Updated Fri, December 09th, 2022

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
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Placer River
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Skookum Drainage
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Turnagain Pass
Closed
The Forest has issued a closure order for Turnagain Pass due to inadequate snow cover for resource protection. Conditions are being monitored daily. 22” of snow exists at the parking lot. Another storm on Sunday/Monday 12/11 may just do it.
Twentymile
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Seward District
Carter Lake
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Lost Lake Trail
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Primrose Trail
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Resurrection Pass Trail
Closed
Closed to motorized use for the 2022/23 winter season per Forest Plan. Open next season.
Snug Harbor
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
South Fork Snow River Corridor
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.
Summit Lake
Closed
The Forest has issued a closure order due to inadequate snow cover for resource protection. Conditions will be monitored daily. Scheduled opening would have been Dec 1st.

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This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area. This advisory does not apply to highways, railroads or operating ski areas.