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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Fri, March 21st, 2014 - 7:00AM
Expires
Sat, March 22nd, 2014 - 7:00AM
Forecaster
Graham Predeger
Avalanche risk The Bottom Line

A MODERATE avalanche danger continues to persist above treeline where weak snow exists above and below a series of crusts.   The probability of triggering a large avalanche today is low but the consequences remain high making safe travel protocol in the mountains right now absolutely critical.

Below treeline and on slopes under 35 degrees the avalanche danger is  LOW  today.

Please take a look at the Observations page for several write-ups CNFAIC staff has been able to compile of some of last weekends large, human-triggered avalanches.

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Fri, March 21st, 2014
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
  • Deep Persistent Slabs
    Deep Persistent Slabs
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
More info at Avalanche.org

Almost a full week has passed now since any reports of major avalanche activity in the backcountry, and with people pushing into bigger terrain without incident yesterday this points toward a stabilizing snowpack. 

We do know however that weak snow still exists below the March 10-14th storm cycle that produced a slab up to 5’ deep.  It is becoming increasingly more difficult to upset this weak layer but if affected the resulting avalanche will be large and potentially un-survivable.  Tracks on a slope do not correlate to stability when dealing with a deep slab avalanche problem.  Shallow spots in a slab are likely areas to trigger an avalanche up to 5’ in depth today.  These may be difficult to recognize but some clues to a shallow, tapering slab include areas near rock or tree outcroppings or directly adjacent to wind-stripped terrain.

                            This photo from the Crested Butte Avalanche Center is a good illustration of how a slab tapers.  
                            Likely trigger spot for this avalanche would be near the lower right corner of the photo where the
                            slab is thin and a human is more likely to affect the weak layer.

If your tolerance for risk is taking you into bigger, steeper terrain today it is fundamental that you and your group exercise safe backcountry travel protocol.  This includes communicating travel plans, escape routes and islands of safety.  Expose only one person at a time on a slope and re-group in safe areas well away from run-out zones.

Avalanche Problem 2
  • Cornice
    Cornice
Cornice
Cornice Fall is the release of an overhanging mass of snow that forms as the wind moves snow over a sharp terrain feature, such as a ridge, and deposits snow on the downwind (leeward) side. Cornices range in size from small wind drifts of soft snow to large overhangs of hard snow that are 30 feet (10 meters) or taller. They can break off the terrain suddenly and pull back onto the ridge top and catch people by surprise even on the flat ground above the slope. Even small cornices can have enough mass to be destructive and deadly. Cornice Fall can entrain loose surface snow or trigger slab avalanches.
More info at Avalanche.org

Strong solar radiation late in the day continues to push cornices toward their natural breaking point.  Add a skier or snowmachiner on a ridge in close proximity to one of these backcountry bombs and cornice failure will be possible.   Your best bet to mitigate this problem today and everyday is to give cornices a very wide berth when travelling on ridges and limit your exposure when travelling beneath. 

Weather
Fri, March 21st, 2014

The first day of Spring yesterday did not disappoint with sunny skies, temperatures reaching into the mid-30’s at 1,000′ and light to moderate winds out of the east.  

Today we can expect partly cloudy skies by this afternoon, winds out of the east in the 10-25mph range and temperatures again warming into the mid to high 30’s by the heat of the day.  Looking into the weekend an upper level ridge will persist over the mainland, keeping southcentral Alaska mostly sunny and completely dry at least through early next week.

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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.