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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Wednesday, February 26th 2014
Created: Feb 26th 6:06 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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The Bottom Line

The avalanche hazard is MODERATE below treeline today for wet loose and wet slab avalanches.  Warming temperatures coupled with light rain will weaken the snow surface, creating the potential for dangerous wet slab avalanches up to 2’ in depth and wet loose avalanches to knock people over in steep terrain.

Above treeline the hazard is also MODERATE.  There is potential for newly formed slabs up to a foot in depth to be human triggered in steep upper elevation starting zones.  These relatively smaller slabs have the potential to pull out deeper weak layers in the snowpack and release slabs up to 3’ in depth.

Wet avalanche concerns will become more widespread into the evening hours as freezing levels climb to ridgetops.


Primary Concern

Temps around the forecast area have been steadily increasing this morning.  Light rain and snow will begin to trickle into the region throughout the day.  It will be possible for people to trigger wet slab avalanches anywhere from 6 inches to 2 feet in depth on steep slopes.  Old stiff wind slabs that formed 3 days ago will become more susceptible to triggers as temperatures rise and freezing levels climb in elevation.

Wet loose avalanches are also a concern today, especially in steep terrain above terrain traps.  Slow moving wet sluffs have the potential to push people into trees, over cliffs and into gullies.  Pay attention to the snow surface.  If you or your skis, board or snowmachine is beginning to sink more than a few inches below any damp surface, it is time to head home.  Temps will continue to climb through the day and into the night.


Secondary Concern

We continue to find weak snow between the January crust and the Feb snow.  This layer has been gaining strength over time.  It will be difficult to trigger an avalanche at this layer, but warm temps and moderate loading (in the higher elevations) will increase the chances of pulling out slabs up to 3 feet in depth.  Steep terrain over 40 degrees should be treated with suspicion today.  The most likely scenario for activating these deeper weak layers will be wet loose/slab, or storm slab avalanches moving downslope and stepping down to the weak snow above the January crust.


Additional Concern

In the higher elevations new snow and strong Easterly winds will build new slabs that will be sensitive to the weight of a person or snowmachine later in the day.  Slab depths will start out small and become greater by evening.  Slabs up to a foot in depth are possible by the end of the day in leeward upper elevation (above 3,000’) starting zones.   Given the warm nature of this storm, expect these slabs to “stick on” to the old snow surface relatively well.  These slabs will be most sensitive as they are forming.


Mountain Weather

In the past 24 hours temperatures have been on a steady increase.  Ridegtop temps have been climbing towards the freezing mark, with Seattle Ridge reading 32 F at 4 am this morning.  Sunburst weather station at 3,812’ has averaged 25 degrees F.  There has been a marked uptick in winds this morning as well, with Sunburst reporting 48mph average at 4am.  24 hour average at this station was 17mph with a max gust of 67 mph. 

Today expect a warm and wet day.  Precipitation will start this morning and will initially be in the form of snow above 2,400’.  Temperatures at 1,000’ will reach 40 degrees F.  Rain/snow line should hover around 2,000’ and gradually climb through the day.  We can expect to see up to 5” of new snow in the higher elevations with rain in the lower elevations.  Rain and snow will continue into the nighttime hours with freezing levels climbing above ridegtop level, in the 4,000’ range.

The long term outlook is complex.  Models are struggling to depict an consistent look into the weather beyond tomorrow.  The good news is that the spike in temperature should be short lived.  We can expect to see temps back to normal by the end of the 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: Mar 15, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
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.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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