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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Tuesday, December 4th 2012
Created: Dec 4th 6:53 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.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
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The Bottom Line

BOTTOM LINE
Upper elevation, steep slopes still harbor a poor snowpack structure and the danger in these areas remains MODERATE. If you are venturing onto steep slopes above 3,000ft the possibility exists to trigger a slab breaking near the ground. The likelihood is on the decline but the consequences are still high. Otherwise, we are seeing a mostly LOW avalanche danger where the majority of people have been recreating. These LOW danger areas are below treeline and above treeline where no slab exists. Watch for sluffing in the loose, weakening snow at all elevations.


Primary Concern

With unrelenting cold and calm weather, our shallow snowpack continues to degrade into weak, sugary snow exposing more rocks daily. At the upper elevations this process has been slower and a poor snowpack structure persists in certain areas, which is our primary concern. Though the only avalanche activity we have heard of or seen for the past 10 days has been sluffs in the weak snow, there is still a concern a slab could be triggered breaking in the old October facets near the ground.

Snowpack observations from yesterday from two notorious upper elevation starting zones point to a steady decline in the potential to trigger one of these slabs. The most concerning places to trigger a slide are those with little or no previous traffic. There are many slopes that remain untouched due to difficult early season/low snow cover access.

Snow surface conditions:
There is a very thin layer of dust on the snow surface that is believed to have been deposited sometime on Friday/Saturday by the strong winds channeled through the Mat-Su Valley. The high winds likely entrained particles that were then carried by the NW winds through Turnagain Arm and deposited in our forecast zone. The dust on snow became more visible with elevation yesterday.

Above treeline a scattered thin wind crust can be found on the loose snow surface in exposed areas. Below treeline there is still very loose, unsupportable snow which is sitting under some quite impressive surface hoar growth.

Sidenote: With the earthquake yesterday evening, I'm wondering (or more accurately hoping) if any facets were shaken off the slopes?


Mountain Weather

Mid-level clouds moved in from the east yesterday associated with a multipart low pressure system spinning in the Gulf and even dropped a flake or two on Turnagain Pass. The clouds look to have reminded overnight and despite the cover, which helps to “hold the heat in”, temperatures have decreased to a new seasonal low at all elevations, except sea level. Ridgetop weather stations are reporting -4 to 0F while treeline stations are -2 to 3F. The inversion is still firmly in place with sea level and valley bottoms in the -15 to -10F range. Expect clearing skies and temperatures to rise 5 degrees or so throughout the day. Ridgetop winds are luckily still light from the northeast, 2-5mph gusting 5-10mph, where they should remain today.

We are still waiting for snow and looking at the longer term model forecasts in hopes of seeing a “fire hose” of moisture pointed at us. Unfortunately, we are going to have to keep waiting through the week - but it does look like there is hope for Saturday. It may not be the fire hose we want, but at least it is a substantial change in the pattern and we should finally see some precipitation.

 


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). 

Kevin will issue the next advisory Wednesday morning, December 5th.

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: Feb 19, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenAccess is thru the gate on the right side of the parking lot as you drive toward the outhouse. Please park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: Open
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

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.


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