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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Saturday, December 8th 2012
Created: Dec 8th 6:23 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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

AVALANCHE WARNING BEGINNING TODAY AS STORM SNOW BUILDS

The game changing storm is due to arrive today with peak intensity sometime this evening.  This combination of a big snow and wind event over the top of a shallow and extremely weak snowpack will turn the backcountry dangerous very quickly today.  We know avalanches will happen from this cycle, it's just a question of how bad it will get and when the peak danger will happen.  Through the daylight hours as the new snow builds, the danger rating will be CONSIDERABLE.  Later this evening as the new snow depth gets beyond 1 foot the danger rating will increase to HIGH with very dangerous avalanche conditions.  All avalanche senses need to be on peak alert if you plan to travel in the mountains this weekend.


Primary Concern

Snowfall totals in the mountains are expected to be 10-18 inches today, with another 10-16 inches tonight.  East wind at ridgetops will be 50-75mph.  If this proves true, avalanche danger will reach HIGH sometime late today.  Fresh snowfall and high wind will create wind slabs at upper elevations.  The timing of the storm may catch people off guard as they try to use the Saturday opportunity before the accumulation gets too deep.  With the blizzard warning in effect and a very weak base snowpack, it will not take a lot of snow for avalanche conditions to change quickly.  Watch the changes as they happen today and be prepared to find a safe route back to the car before it gets too dangerous.


Secondary Concern

As the storm snow and wind slabs build, they will be resting on top of all the junky facets and surface hoar that built over the last month of cold dry weather.  This is a really bad combination, and the first test in quite a long time.  Everything about this setup is screaming bad news.  All the new snow will fall on 2 feet of collapse-prone ball bearings.  We can expect avalanches to behave more dangerously than normal, breaking at the new/old snow interface or at the ground and running far and fast.  Propagation potential today will depend on the temperature of the storm (the density of the snow) and the intensity of the wind to build cohesive slabs.  Even a small amount of cohesiveness in this new layer will allow for widespread connectivity of the slab. 

If you can't already tell, I'm pretty worried about the storm today!


Mountain Weather

Yesterday was a cloudless and calm day in the mountains.  This morning, temperatures have risen up to 10 degrees in some areas and wind is reaching into the 30s at the ridgetops.  As of 6am snowfall has not started in Turnagain Pass or Girdwood, but radar in Prince William Sound is starting to show the precipitation approaching. 

The blizzard warning is active across our region starting at 10am, so confidence in this storm is high.  Expect snow - 10-18 inches today, and 10-16 inches tonight with 1.5 inches of water equivalent.  East wind is expected to blow 50-75mph at the ridgetops.  Temperatures will remain below freezing today, with slightly warmer temperatures tomorrow in coastal areas such as Seward and Whittier. 

The weather that happens today will drive the overall avalanche danger.  What you see is what you get, so pay attention if you want to play in the mountains today.  New snow approaching 1 foot depth will take us into dangerous avalanche conditions where trying to outsmart the problem will become impossible. 


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). 

Wendy will issue the next advisory Sunday morning, December 9th.

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: Apr 11, 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: OpenWide swaths of open river in the Placer Valley. Travel with extreme caution!
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: ClosedClosed for the remainder of the 2017 season.
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

Subscribe to the Turnagain Area Avalanche Advisory:

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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