Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, March 14th 2014 7:00 am by John Fitzgerald
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is HIGH at all elevations.  Heavy snowfall combined with strong winds have created unstable conditions in the backcountry.  Slabs 1-5’ in depth could release naturally today.

Dangerous avalanche conditions exist.  Travel in avalanche terrain is not recommended today.

 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Below Treeline / Below 1,000' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Avalanche Problem 1

Rapid loading has been occurring overnight.  New snow amounts over the past 24 hours are in the 12-18” range on Turnagain Pass.  This newest load has come on the heels of over 3 feet of new snow from earlier in the week.  An additional 10" of snow today will only add to the problem. This all boils down to a simple rule of thumb: snow does not like rapid change.

Included in Storm Snow concerns are Wind Slabs.  Starting zones, cross loaded gullies and leeward slopes hold the potential for harboring sensitive wind slabs.  Dense thick slabs up to 5 feet in depth have the potential to release naturally today.  These slabs will be most sensitive as they are forming.  Be on the lookout for rounded and smooth snow surfaces.  Shooting cracks will be the first indicator that you are on a wind slab.

Failure within the storm snow layers could be anywhere from 1-5' deep today.  Avalanches occuring in these upper layers have the potential to step down to deeper layers in the snowpack.

Avoidance of avalanche terrain is essential today.  This includes staying off of slopes 35 degrees and steeper, avoiding wind loaded areas and being far away from runout zones.  It is critical to know what terrain is above you, especially when visibility is poor.

Avalanche Problem 2

While the arrival of Winter Part III is welcome from a recreational perspective, it has also created a Deep Slab problem.  Prior to March 10th the snow surface was comprised of a well developed layer of weak snow sitting on a crust.  This combination was observed throughout the forecast area.  That interface is now buried by as much as 5’ and on average over 3’ of snow.  While it might be difficult to immediately affect this interface due to its depth, it is still the layer that is most concerning. (see video HERE for an explanation of this issue)

Avalanches failing at this interface have the potential to be high volume and unsurvivable.  The travel advice related to this problem is the same-avoid being on or in the runout of avalanche terrain.

Additional Concern

Warm temps and rain at sea level will allow for the chance of encountering wet loose avalanches in steep terrain.  The observed rain snow line was around 500’ in elevation last night.  If you find yourself slogging in wet snow below 1,000’ it will be important to stay off of any terrain over 35 degrees.

Mountain Weather

The snow continues to pile up!  In the past 24 hours the Center Ridge SNOTEL site on Turnagain Pass has picked up 18” of snow with 1.6” of water with similar amounts in the Girdwood Valley.  Ridgetop winds (Sunburst station) have averaged 52 mph out of the East with a max gust of 97 mph.  Temps on ridge tops have remained in the low to mid 20s F.  The rain/snow line has hovered around 500-800’.

Today expect a continuation of snow and wind.  Another 6-10” of snow with .65” of water is possible today.  Temperatures at 1,000’ will be around 32 F.  Winds will back off slightly but still average in the 35-45 mph range.

Snowfall should taper off tonight.  Temperatures (at 1,000') will also drop into the teens by the nighttime hours.  The extended outlook shows more of the same (snow & wind) heading into the weekend and early part of next week.

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: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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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