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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Wednesday, December 18th 2013
Created: Dec 18th 6:56 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 danger today is generally LOW with pockets of MODERATE danger where human triggered avalanches are possible in steeper terrain. Furthermore, if todays approaching storm moves into our region earlier than forecasted, ample winds will act to increase the avalanche danger.


Primary Concern

Storm snow from Dec. 13/14th continued its settling process as relatively warmer temperatures (above 0 F) today will promote bonding, allowing more of a consistent or interconnected slab across a given slope.  It is unclear still if warmer temps today will do much to affix last weekend’s storm snow to our December drizzle crust from 12/7.  We have had several reports of small, skier triggered soft slabs running on this crust over the last few days.

The crust is easy to find as it proves supportable to a skier and is widespread throughout the Turnagain zone.  Given time it will continue to break down and become absorbed into our mid-winter snowpack but right now we are paying particular attention to how any new load of snow will react on this bed surface.  Continue to pay attention to steeper, rocky terrain or convex rollovers where you may pull out a soft slab pocket today.

Moreover let's not lose site of what lies below.  The lower half of our snowpack consists of very weak, faceted snow.  I suspect a big enough trigger such as a snowmachine may be able to penetrate this rotten layer and produce an avalanche.

 


Secondary Concern

Our surface still consists of low density, loose snow that is ripe for wind transport with the coming storm (see mountain weather below).  New surface hoar has also formed over the last couple of cold and clear nights to cap our snowpack.  If winds pick up early enough in the day today, we could see wind slabs forming below ridges and on cross-loaded slopes prior to nightfall.


Mountain Weather

Yesterday temperatures were stubborn to break single digits.  Winds were generally light form the north and northwest allowing valley fog to stay in place for much of the day in low lying areas while anyone in the upper elevations was rewarded with clear skies and a very low (on the horizon) sun.

Expect today to be a day of transition as mid and high level clouds move in to our area ushering in the arrival of what looks to be a quick, yet potent blast of winter weather.  A strengthening low-pressure system to our south will arrive this afternoon/ evening packing SE winds and ample snow.  There is a Blizzard Warning in effect for 6PM this evening.  The peak intensity of this storm looks to hit the eastern Turnagain Arm region overnight and if the system lines up favorably, we could wake up tomorrow with 12-18” of new snow.  The exact track of this low will play a big role in wind direction and specifically what areas are favored with snowfall, but in short precip will be in the form of snow across our region and winds will be moderate to strong overnight, creating those blizzard conditions. 

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

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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
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