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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Wednesday, December 26th 2012
Created: Dec 26th 7:00 am
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.
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The Bottom Line

BOTTOM LINE
Dangerous avalanche conditions remain in the backcounty.
Between 3 and 4 feet of snow has fallen during the past 48 hours on a very tenuous and weak pre-existing snowpack. This coupled with additional snow and strong wind this afternoon will keep the avalanche danger HIGH. Human triggered avalanches are certain both above and below treeline and travel in the backcounty is not recommended.

 

ANNOUNCEMENTS
The AK DOT will be conducting avalanche hazard reduction work today on the Seward Highway between mileposts 99 to 83 (Bird-Twentymile River). Motorists should expect delays of up to 45 minutes between 8:30 AM and 5:00 PM. Updates will be posted at 511.alaska.gov.


Primary Concern

The strong easterly winds that accompanied the Christmas storm have died down slightly overnight but will be on the rise through the day today as another system is headed our way this evening. We have little information for above treeline and areas receiving wind due to low visibility and dangerous avalanche conditions but we can expect a good natural avalanche cycle occurred during the past 36 hours and will ramp up again this evening and into tomorrow with additional snow and wind.


Secondary Concern

With the significant round of snowfall in the past two days, we have given our early season weak snowpack a good shock to the system. It was no surprise to see widespread avalanche activity yesterday. All the new snow has bonded well to itself but the problem is it is sitting on varying layers of weak faceted snow that will keep it from bonding to the mountain sides. This means avalanches are failing below the new snow making them 3-4' deep and deeper in windloaded areas - slabs this thick are unmanageable. Observations from below treeline yesterday give a sense of this problem. As the new snow settles with the warming temperatures today the pack will shift from mostly unconsolidated new snow to a denser slab which will add to the already unstable situation. It is great to see so much new snow (a more than doubling of the pack) but patience will be the key to staying safe in the backcountry.


Mountain Weather

It has been an extra white Christmas for the Eastern Turnagain Arm with between 3 and 4 feet of snow falling since the morning of the 24th. Yesterday, Turnagain Pass saw an additional foot of accumulation with storm totals around the area listed below. As this system exits to the north this morning another one is right on its heels and will usher in warmer wet conditions for this afternoon through Thursday evening. Snowfall amounts look to be in the 10-16" range.

Total snow accumulation beginning early morning on the 24th:

Girdwood Valley – ~45” snow with 4.5” of water equivalent
Turnagain Pass – ~35” snow with 3.4” of water equivalent
Summit lake – ~8” snow with 0.8” water equivalent

Snow densities have averaged around 10% region wide, this next storm is warmer and should put down higher density snow along with rain or a rain/snow mix at sea level. Winds have died down overnight (E at 20mph gusting 40mph) but are forecast to increase again through the day (E in the 50-60mph range) with the rapid approach of the next system. Temperatures will rise a couple degrees today to the mid 20's F at the ridgetops and low 30's at sea level.

 


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).

Graham will issue the next advisory Thursday morning December 27th.

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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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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