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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Tue, March 3rd, 2015 - 7:00AM
Expires
Wed, March 4th, 2015 - 7:00AM
Forecaster
John Fitzgerald
Avalanche risk The Bottom Line

The avalanche danger is MODERATE in the Alpine, where slabs 1-2′ in depth could be triggered in steep terrain.   Triggering these slabs is on the low end of the scale but consequences remain high enough to warrant careful snowpack and terrain assessment.

The danger is LOW at Treeline and below where triggering an avalanche is unlikely.

Despite it being early March, early season conditions exist on the approaches.   Ice, alder stumps and rocks are hazards to avoid when traveling to and from the treeline elevations today.

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Tue, March 3rd, 2015
Alpine
Above 2,500'
Moderate (2)
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
Moderate (2)
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
  • 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

Weak snow that has been buried for 3 weeks continues to lurk 1-2 feet below the surface.  This layer has gained significant strength in that time.  Bonding between the “late January” facets and overlying slabs has improved to the point where it has become difficult to trigger an avalanche on this layer.  Some intermediate weak layers can be found in isolated locations and are buried about 1 foot deep.  Slabs resting on these layers are also generally difficult to trigger.   Tests have been showing propagation potential on the decline, but it is still possible for an avalanche, if triggered, to propagate across portions of slopes.  

Despite these improving trends it is still important to treat steep and complex terrain with suspicion in the Alpine.  Today it will be important to follow good travel protocol.  Assess the terrain you are on and minimize your exposure accordingly.  Avoid trigger points on terrain over 35 degrees, travel one at a time on suspect slopes, use islands of safety and communicate your decisions and plans within your group.

Avalanche Problem 2
  • 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

Ridgetop winds have been in the 20-30 mph range since yesterday morning.  Very shallow stiff slabs may be encountered today on steep (40 degrees and over) leeward slopes.  These slabs will be small, around 4-6” deep and exist in small pockets.  While the volume of any wind slabs triggered will be low, it will be important to avoid them when travelling above terrain traps such as cliffs, gullies and trees.

Weather
Tue, March 3rd, 2015

The past 24 hours saw mild temps with moderate ridegtop winds.   Skies were mostly cloudy and less than a trace of new snow fell in the upper elevations.

Today expect more of the same.   Winds will be out of the East at 15-20 mph.   Very light snow under mostly cloudy skies will fall with a max of 2 € of accumulation.   Rain/snow line will be around 1,000′.   Temperatures at 1,000′ will be in the low to mid 30s F.

The extended outlook is showing a continuation of showery precipitation through the week, as a series of weak lows move through the area.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 34 0 0 40
Summit Lake (1400′) 34 0 0 7
Alyeska Mid (1700′) 34 trace .06 22

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′) 24 ENE 20 51
Seattle Ridge (2400′) 26 NW 29 59
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Riding Areas
Updated Tue, April 20th, 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
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Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
Skookum Drainage
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The Skookum Valley is closed to snowmachines. This closure occurs annually on April 1 as per the CNF Forest Plan.
Turnagain Pass
Open
Twentymile
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Seward District
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Resurrection Pass Trail
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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.