Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, November 25th, 2014 - 7:00AM
Expires
Wed, November 26th, 2014 - 7:00AM
Forecaster
Graham Predeger
Avalanche risk The Bottom Line

The avalanche danger is LOW at and above treeline elevations today.   There still exists a possibility to trigger a wind slab in isolated terrain features, particularly in the higher elevations.   These wind slabs are variable in depth, and at the mid-elevations are resting on a slick rain crust. The continued lack of snow coverage results in No Rating at our lower elevation band below about 1500′.   Another real hazard today deals with the potential for injury from collision with shallowly buried stumps, rocks and other hazards given the early season snowpack.

The next advisory will be Thursday morning (Thanksgiving Day!) at 7am.  
Outlook for Wednesday:  
With high pressure building into south-central Alaska today and through Wednesday, the weather and resulting avalanche conditions are expected to be very similar for tomorrow.

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Tue, November 25th, 2014
Alpine
Above 2,500'
Low (1)
Avalanche risk
Treeline
1,000'-2,500'
Low (1)
Avalanche risk
Below Treeline
Below 1,000'
No Rating (0)
Avalanche risk
Alpine
Above 2,500'
Avalanche risk
Low (1)
Treeline
1,000'-2,500'
Avalanche risk
Low (1)
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
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

Surface conditions appear to be shaping up in the Turnagain zone after last weeks onslaught of rain up to about 3,500’ that deposited a stout crust in what is now our mid snowpack.  Yesterday we found variable thickness wind slabs resting on this crust showing signs of good bonding.  This wind slab is capped off by 6-8” of new low-density snow that fell on Saturday and Sunday with very little associated wind.  Though no red flags were noted yesterday and stability tests did not produce any results, confidence in this forecast is low due to limited information and lack of travel into the upper elevations (above 3,000’) thus far.  Where we expect this mid-pack rain crust to finally disappear (~3,500’) wind slabs could be a bit touchier.  Approach these higher elevation alpine slopes with caution and evaluate the snow and terrain carefully before committing to a slope.

 

 

 

 

 

 

 

 

 

 

 

 

                     

 

                              An ‘average’ snowpit in the mid-elevation band.  Sunburst @ ~ 2,900 feet.

Avalanche Problem 2
  • Glide Avalanches
    Glide Avalanches
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.
More info at Avalanche.org

Glide cracks have been mostly covered up by this latest storm.  In this instance though, out of sight does not mean out of mind.  Keep a keen eye out for any new cracks opening up and steer clear of these dangerous features.  Conditions are ripe for new glide crack formation, particularly in the Turnagain area.  There is much to understand about this phenomenon but what is known is that these cracks can release very suddenly and without a real trigger.  Your best bet is to limit your exposure by steering clear of glide cracks.

An additional concern today and for the foreseeable  future involves the hazards associated with an early season snowpack.  Many rocks, stumps and previous glide cracks are thinly covered with this most recent storm.  Keep it conservative and in control, particularly in the lower elevations where snowpack is thinnest.  There is A LOT of winter to still be had and nobody likes being injured, especially early in the season!

 

 

 

 

 

 

 

 

 

 

 

 

Snowpack is thin at the lower elevations.  Expect to hike up to a half hour (Turnagain zone) before putting skis on.

Weather
Tue, November 25th, 2014

Over the last 48-hours we’ve seen 6-8 € of new low-density snow fall at the mid and upper elevations with just a dusting at the highway level (1,000′) through Turnagain pass.   Winds have been the big change over the last 2-days dropping off dramatically as we received this last bout of snow and averaging less than 10mph from the SE.   The rain/ snow line continue its march toward sea level with another ~1,200 -1,400 vertical feet to go.

Today we may see a few lingering flakes in the eastern Turnagain arm area with light winds (4-8mph) from the West.   Temperatures will continue a slight drop today and overnight with lows dipping into the mid-20’s at 1,000′.   This evening and into tomorrow we’ll usher in an upper ridge of high-pressure that should leave us under blue skies and light to moderate winds on Wednesday.

Below are the new weather tables for this season that give a brief snapshot of the past 24-hours for key weather stations in Turnagain Pass, Summit Lake and the Girdwood Valley.
Also, for a more in-depth look at our seasonal weather history click HERE.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 31   0 0   19
Summit Lake (1400′) 25    0   0   0  
Alyeska Mid (1539′) 35    0   0   2  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 25   SE   5   14  
Seattle Ridge (2400′)  28  variable 7   12  
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Riding Areas
Updated Tue, January 12th, 2021

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
Open
No parking in turnaround at end of the road near the outhouse.
Placer River
Open
Early season conditions exist, including thin ice on rivers, swamps and lakes. Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
Skookum Drainage
Open
Early season conditions exist, including thin ice on rivers, swamps and lakes. Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
Turnagain Pass
Open
Twentymile
Closed
Seward District
Carter Lake
Open
Lost Lake Trail
Open
Primrose Trail
Open
Resurrection Pass Trail
Closed
Closed for the 2020/21 winter season.
Snug Harbor
Open
South Fork Snow River Corridor
Open
Summit Lake
Open

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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.