Turnagain Area Avalanche Advisory
Wednesday, March 6th 2013 6:30 am by Kevin Wright
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

In the absence of sun today, the danger will be generally LOW.  Warmer temperatures are expected for low elevations today, and combined with a small amount of rain we may see some minor wet loose activity below treeline.  Above treeline we are still finding a lot of mature overhanging cornices that can fail spontaneously at random times.  Overall our snowpack right now is strong, with only a couple weak anomalies that are very difficult to trigger by a person. 

 Show the Complete North American Avalanche Danger Scale
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1

Cornices throughout the region are getting to be very large in most areas, including Turnagain Pass.  The largest natural avalanches in the last 5 days have been as a result of cornice falls.  In Haines a heli-ski guide was killed over the weekend when his party collapsed a cornice.  We got a report of a natural avalanche in the Placer river region yesterday that may have been a cornice failure.

Cornice safety relies on managing exposure.  This means you should limit the time you spend directly underneath overhanging features, especially if temperatures are warm or they are in direct sun exposure.  Traveling directly on ridge tops can be safe, as long as you give a wide berth to any overhanging sections.  When standing on a ridge it can be very difficult to know how far back a cornice might break.  In general, the breaking point is much further back than you might expect. 

The good news related to cornices is that they are one of nature's best slope stability tests.  We get a lot of information from cornice failures when the slope underneath gets pummeled by thousands of pounds of hard cornice chunks.  Based on our observations of cornice failure, the current snowpack is showing minimal reactivity to large triggers.  This means that backcountry travelers are unlikely to trigger a slab avalanche in the backcountry today.

The one recent exception was a cornice that triggered a deep slab on the mid elevation ice crust in steep terrain in the Girdwood valley on Sunday.

Avalanche Problem 2

Yesterday's sunny skies were hammering southerly slopes with solar radiation.  Temperatures overall were not much above freezing, so the warming effect was minimal but still noticeable.  Some direct south facing slopes at low elevation showed a small amount of loose wet avalanche activity.

Sun is not in the weather forecast today, but temperatures are expected to reach into the low 40s at sea level.  This may be enough to melt the surface crusts and cause more minor loose avalanche activity by the afternoon. 

Mountain Weather

Yesterday was sunny and calm with mild temperatures.  Our last big shot of moisture was 6 days ago, and the snowpack has been settling and strengthening since then. 

Today, rain and snow is in the forecast.  Actual amounts predicted are very minor, leading me to believe that new precipitation today will not have a significant effect on the avalanche danger.  The rain/snow line is predicted at 700 feet today.  Temperatures may reach into the low 40s at sea level.  Expect light wind to 15mph from the south. 

Tomorrow a larger storm system is moving into our region with high wind, rain, and snow forecasted.  We can expect the avalanche danger to increase for Thursday and Friday as a result of this coming storm.

Graham will issue the next advisory on Thursday, March 7th.

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).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Mar 22, 2019 )

Glacier District
Johnson Pass: Open
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
Summit Lake: Open

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.

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