Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, December 29th 2013
Created: Dec 29th 6:38 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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Silverton Mountain Guides
The Bottom Line

There remains a MODERATE avalanche danger today for triggering a slab avalanche 12-18” deep. The chances for finding and triggering a slab will be most pronounced on steep slopes (approaching 40 degrees and steeper) and on all aspects near and above treeline. Conditions today remain similar to those on Thursday when a skier triggered a sizeable avalanche on Turnagain Pass.

From outside of our advisory area we had a report come in yesterday of a skier triggered class 2 avalanche (no one caught). This was in the South Fork zone north of Anchorage. You can read it HERE.

Primary Concern

For most folks that have been in the backcountry lately it is hard not to notice the collapsing in the snowpack. Other than a few avalanches in the past week, this has been our prominent ‘obvious clue’ as to the weak snow lying 12-18” below the surface. If you look at the two observations sent in yesterday, both highlight collapsing (or whoomphing). You can see them HERE and HERE. Other red flags are found by digging in the snow. However, a collapse trumps all and essentially means that if a slope is steep enough chances are it will avalanche.

With weak layers in the pack that are hard to assess from the surface, keeping with safe travel practices will help to hedge your bets if riding/skiing on steep slopes. These include watching your partners, exposing only one person at a time and having an escape route planned if the slope avalanches.

Below is a cross section of the snowpack at 3,200'. You can see a vertical crack in the 'slab' and the weak snow (lighter colored) below a crust. This if from a snow pit on Magnum, SW facing. - more details and video HERE.


We received 2-3" of snow from Friday night that was blown into drifts on the ridgelines. Cornices grew a bit with this event and some small to medium natural cornice failures were seen yesterday. This snow has shown signs of bonding well with the surface and is now part of the 'slab' mentioned above.

Below treeline the slab is losing its cohesion and the pack is unsupportable. Though there is some localized collapsing in the alders, triggering an avalanche is unlikely.

Mountain Weather

During the past 24-hours we have seen a slight warm up above treeline (20-25deg) and a slight cool down at sea level (upper 30’s to low 20’sF) due to minimal cloud cover producing a weak inversion. Winds have been light from the Southeast and have switched to the Northwest overnight. We only picked up ~3” above treeline with Friday night’s snow event.

Today we will see a weak disturbance move over us from the Gulf bringing mostly cloudy skies and continued warm temperatures. Ridgetops will be in the mid 20’sF with winds shifting back to the Southeast and picking up through the day to the 20mph range by the evening hours.

There is a possibility for precip on Tuesday into Wednesday as a warm low pressure system moves in from the South. How much will depend on the track this low takes but it is fairly warm with rain at sea level likely.


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 )

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.

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