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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, February 4th 2013
Created: Feb 4th 6:30 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

The avalanche hazard is MODERATE above treeline today, where recent snow and winds have formed slabs that will be sensitive to human triggers in the higher elevations today.  The hazard below treeline is LOW today, where the snowpack has been able to absorb light rain and wet snow to the point where it will be difficult for humans to trigger avalanches today.


Primary Concern

Light to moderate snowfall over the last three days has formed new slabs that will be easy to trigger in steep wind loaded terrain today.  In areas that have not received wind and on slopes under 35 degrees the new snow has been bonding well to older snow surfaces.  All reported avalanche activity in the past several days has occurred around the 2,800' elevation.  This is due in large part to snow falling on a firm surface that has encouraged propagation across slopes.  While these avalanches have released snow in relatively large areas, the volume has been low enough that people have been able to avoid injury and burial.  While we have limited information from the upper elevations lately, snowfall amounts and winds have been high enough above 3,000' to create dense slabs up to 18 inches in depth.  Throw into the mix new snow and winds today and slabs will increase in size and depth.  Sticking to slopes under 35 degrees and avoiding wind loaded starting zones will allow for enjoyable riding and skiing conditions today.


Secondary Concern

The deep slab problem is elevation dependent.  The snowpack between 1,000 and ~2,000 feet has been through four periods of warm temps, light rain and wet snow in the last month.  This has helped to change the structure of the snow at the ground to the point where it is generally not a concern.  However, above ~2,000 feet the snowpack is still in transition; snow pits have shown us that the weak snow at the ground is changing for the better.  However, as you gain elevation the weak snow at the ground is more intact and more of a problem to pay attention to.  Avoiding thin spots, steep rollovers, and terrain that doesn't offer exit options is the best way to stay away from this problem.

It has been three weeks since a deep slab avalanche has been reported in the area.  It is now very difficult to affect weak layers at the ground.  The consequences still remain high, as a deep slab avalanche once triggered could entrain high volumes of snow and do a lot of damage.


Mountain Weather

Turnagain Pass has picked up 1-2" of new snow in the past 24 hours.  Winds yesterday were light but have picked up this morning and are now blowing 20mph out of the East with gusts to 36.  Temps have been mild with freezing levels hovering around the 1,000' elevation.

Snowfall should continue today, with possible accumulations in the 2-4" range.  Ridgetop winds will blow out of the S and SE between 15-20 mph with gusts up to 30mph.  Temps at 1,000' will be just below freezing.

A generally unsettled pattern will continue this week as a series of disturbances move through the area.  Snowfall amounts will continue to be light and temps should remain mild and similar to what we have seen over the last several days.

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Wendy will issue the next advisory tomorrow morning, February 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: May 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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