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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Wednesday, April 3rd 2013
Created: Apr 3rd 6:45 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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Arctic Air Walkers
Special Announcement

The Skookum drainage is now closed to motorized travel for the remainder of the season.


The Bottom Line

If you haven't already noticed, we've entered a spring pattern of warm days and intense sun affecting the snowpack.  The avalanche danger will start the day at LOW and gradually rise to MODERATE as the day heats up.  South faces should be avoided late in the day as some natural avalanches have been happening over the last few days.

Other problems can be found on shady aspects, including triggerable wind slab and buried surface hoar.


Primary Concern

RECENT ACTIVITY

The most notable avalanche we saw yesterday was off Goat Mountain in the Girdwood valley.  We believe a cornice failed due to daytime heating and triggered a slab beneath.  This is a common occurrence in this place this time of year.  The travel distance of the avalanche was impressive, and farther than I've personally seen that path slide.  


With continued high daytime temperatures, wet avalanche activity in the afternoon remains the most likely problem to see today.  There are numerous examples of this happening over the last few hot sunny days.  

Heat induced avalanches are easy to avoid, especially when nighttime temperatures dip below freezing as they are currently.  Sometime in the mid afternoon when the snow surface becomes soft or wet, it's time to avoid south faces, including spending time beneath south faces.  


Secondary Concern

The cornice problem is really an extension of the heat problem.  As the sun bakes the mountains and temperatures rise in the afternoon, unstable features like cornices lose strength and may fail spontaneously.  

This problem can be especially dangerous if they trigger larger slabs on the slopes below, as happened on Goat Mountain yesterday.

 

ADDITIONAL CONCERNS

Even shady aspects have had some avalanche activity since the last major snowfall.  Some of these can be attributed to wind slab over loose near-surface-facets.  Yesterday we found a low elevation north aspect slab that failed on buried surface hoar in the Placer valley.  Everything we've seen with this character is breaking at the recent storm snow interfaces ~12-24 inches deep.  These are common enough that all steep lines should be treated with a degree of respect.


Mountain Weather

Yesterday the warm and sunny weather continued.  Wind up high reached into the teens and 20s overnight.  Overall the only weather factor contributing to avalanche danger was the sun and warm temperatures.

Scattered rain and snow showers are forecasted today with mostly cloudy skies.  Temperatures are still expected to reach into the 40s at sea level in the afternoon.  If the sun doesn't shine today there will be less concern for wet avalanche activity on south faces.  Wind should be light from the southeast.


Graham will issue the next advisory on Thursday, April 4th. 

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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