Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, January 21st 2013 5:55 am by John Fitzgerald
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Today the avalanche hazard is MODERATE above treeline.  A moderate amount of new snow and wind has created slabs that will be sensitive to human triggers.  The possibility still remains for large and destructive avalanches to be triggered in the higher elevations today.  The hazard below treeline is LOW this morning and will rise to MODERATE, as rising temperatures will slightly increase the chances for humans to trigger avalanches today.

 Show the Complete North American Avalanche Danger Scale
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.
Avalanche Problem 1

Recent snow in the higher elevations have fallen on slick and hard surfaces.  While the snowfall amounts have been modest, the winds overnight have been transporting this snow onto leeward aspects, mainly West to North facing slopes.  With temperatures forecasted to increase throughout the day, expect these slabs to become more sensitive to human triggers.  Expect to see shallow pockets of windslab at mid elevations (up to 1800') in open areas to be the most sensitive today, as these slabs have fallen on a firm crust and will heat up more readily than slabs in the higher elevations today.  On the flip side, these slabs are not as large (<6") as slabs in the upper elevations (>12").  Avoiding steep upper elevation starting zones which have a pillowy or wind affected look will also be important, as these slabs, once released, have the potential to carry people downslope and into terrain traps today.

Avalanche Problem 2

It is important to not forget the poor structure of the base of our snowpack.  Snowpit tests over the past week continue to show weak faceted snow persisting near the ground.  The large dense slabs that formed over the holidays are now able to support a lot of weight.  The chances of initiating one of these slabs is getting more difficult by the day.  If you were to trigger one of these deep slabs, the outcome would be bad, as the volume of snow could be very large.  We are clearly in a dormant period for this avalanche problem, as it has been a week now since any new deep slab activity has been reported.  Unfortunately, the weak snow is being well preserved in many areas and will continue to lurk well below the surface for the forseeable future.  Staying away from areas showing exposed rocks, ground or vegetation will be important in avoiding this problem today, as these are the most likely areas to trigger a deep slab avalanche.

Mountain Weather

In the past 24 hours Turnagain Pass has received ~6" of new snow with .3-.5" water equivalent. Winds have been moderate out of the E and SE averaging 20 mph with gusts to 36 mph.  Temps, which have been on a steady rise overnight have averaged near 32 F at 1800', and in the mid 20s F at 3800'.
Expect clouds to be on the increase through the day, winds out of the East 20-35 mph and a chance of precipitation with up to 3" of new snow possible in the mountains.  Temperatures will climb into the mid 30s F at 1000'.
The extended outlook calls for a greater chance of snow tonight, with precip continuing into the middle of this week.


Wendy will issue the next advisory, tomorrow morning January 22nd.

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: Dec 01, 2018 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed November 21 due to inadequate snow conditions. #hopeforsnow
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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.

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