Turnagain Pass Avalanche Forecast RSS

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ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Issued
Mon, February 4th, 2013 - 7:00AM
Expires
Tue, February 5th, 2013 - 7:00AM
Forecaster
John Fitzgerald
Avalanche risk The Bottom Line

The avalanche hazard is MODERATE above treeline today, where recent snow and winds have formed slabs that will be sensitive to human triggers in the higher elevations today.   The hazard below treeline is LOW today, where the snowpack has been able to absorb light rain and wet snow to the point where it will be difficult for humans to trigger avalanches today.

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Mon, February 4th, 2013
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

Light to moderate snowfall over the last three days has formed new slabs that will be easy to trigger in steep wind loaded terrain today.  In areas that have not received wind and on slopes under 35 degrees the new snow has been bonding well to older snow surfaces.  All reported avalanche activity in the past several days has occurred around the 2,800′ elevation.  This is due in large part to snow falling on a firm surface that has encouraged propagation across slopes.  While these avalanches have released snow in relatively large areas, the volume has been low enough that people have been able to avoid injury and burial.  While we have limited information from the upper elevations lately, snowfall amounts and winds have been high enough above 3,000′ to create dense slabs up to 18 inches in depth.  Throw into the mix new snow and winds today and slabs will increase in size and depth.  Sticking to slopes under 35 degrees and avoiding wind loaded starting zones will allow for enjoyable riding and skiing conditions today.

Avalanche Problem 2
  • 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

The deep slab problem is elevation dependent.  The snowpack between 1,000 and ~2,000 feet has been through four periods of warm temps, light rain and wet snow in the last month.  This has helped to change the structure of the snow at the ground to the point where it is generally not a concern.  However, above ~2,000 feet the snowpack is still in transition; snow pits have shown us that the weak snow at the ground is changing for the better.  However, as you gain elevation the weak snow at the ground is more intact and more of a problem to pay attention to.  Avoiding thin spots, steep rollovers, and terrain that doesn’t offer exit options is the best way to stay away from this problem.

It has been three weeks since a deep slab avalanche has been reported in the area.  It is now very difficult to affect weak layers at the ground.  The consequences still remain high, as a deep slab avalanche once triggered could entrain high volumes of snow and do a lot of damage.

Weather
Mon, February 4th, 2013

Turnagain Pass has picked up 1-2″ of new snow in the past 24 hours.   Winds yesterday were light but have picked up this morning and are now blowing 20mph out of the East with gusts to 36.   Temps have been mild with freezing levels hovering around the 1,000′ elevation.

Snowfall should continue today, with possible accumulations in the 2-4″ range.   Ridgetop winds will blow out of the S and SE between 15-20 mph with gusts up to 30mph.   Temps at 1,000′ will be just below freezing.

A generally unsettled pattern will continue this week as a series of disturbances move through the area.   Snowfall amounts will continue to be light and temps should remain mild and similar to what we have seen over the last several days.

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Wendy will issue the next advisory tomorrow morning, February 5th.

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Riding Areas
Updated Thu, April 01st, 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
Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
Skookum Drainage
Closed
The Skookum Valley is closed to snowmachines. This closure occurs annually on April 1 as per the CNF Forest Plan.
Turnagain Pass
Open
Twentymile
Open
Please do not ride along Railroad tracks. Cross tracks at 90 degree angle and clear the right of way.
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.