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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Kevin Wright  
Wednesday, January 2nd 2013
Created: Jan 2nd 6:42 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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Crews will be conducting avalanche hazard reduction work between Girdwood and Portage Wednesday Jan 2, 2013 between 9am-11am. Expect intermittent delays on the Seward Highway while this work is in progress.


The Bottom Line

The storm flow has backed off a bit last night and today.  A decrease in the storm intensity will decrease the avalanche danger, but does not take us away from "dangerous".  Over the past 8 days we tripled the snowpack on the ground, placing a tremendous stress on a persistent weak layer.  CONSIDERABLE avalanche conditions can be found across a wide region today, meaning that steep slopes should still be avoided.


Primary Concern

This deep slab problem has already shown itself to be very active during the storm cycle.  Now that the precip and wind has lessened, the likelihood of natural avalanche activity will decrease but human triggered avalanches will remain a serious problem.  The longer we wait to jump onto steeper terrain, the less likely we will be to trigger a deep avalanche.  As recently as yesterday we saw large avalanches triggered by the Department of Transportation.  Since that time another 10 inches of snow has fallen in some areas.  Some thoughts on the deep slab problem -

- whumpfing and shooting cracks may not be evident

- standard snowpit tests are not suitable for testing deeply buried weak layers

- a lack of observed avalanche activity is not a reliable indicator of potential hazard.

- Waiting 36-48 hours after significant weather changes will decrease the likelihood of triggering (but not eliminate it)

- In some places we have seen the same slope avalanche twice during the recent storm cycle

- Terrain management is the only reliable prevention tool when snow stability is a problem


Secondary Concern

Wind slab may be a problem above treeline today.  We haven't been able to see avalanche activity within the new storm layers because we haven't been able to access higher elevation areas in the past 8 days.  Recent wind and forecasted wind today may be loading up lee oriented slopes.


Mountain Weather

It's been a wet and wild week, and it isn't finished yet.  The graphs below show Turnagain Pass snow depth and wind from the recent weather events.

snow graph

wind graph

Today's weather looks to be mild by comparison.  Snow showers are expected today, with 2-3 inches of accumulation.  Rain line will be 500 feet.  Southeast wind from 30-40mph during daylight hours.  Increased precip and wind is expected again tonight.  The overall weather pattern is expected to remain active, although not as intense for the remainder of the week.


 

John will issue the next advisory on Thursday, December 3rd.

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 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
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: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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