Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Friday, January 4th 2013
Created: Jan 4th 5:51 am
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
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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The John Byrne Family
The Bottom Line

The avalanche hazard remains at HIGH today above treeline, where over a foot of new snow and winds have added stress to the snowpack.  Above treeline today human triggered avalanches are very likely.  Below treeline the hazard is CONSIDERABLE, where human triggered avalanches are likely.

Primary Concern

The skier triggered avalanche that occurred on Jan 2 is a good reminder that many slopes are capable of producing large, deep and destructive avalanches.  This avalanche showed us a snowpack that is remarkably dangerous, as smaller avalanches occured on adjacent slopes as a direct result of this slide.  This event should be a wake up call to us all.  While the outcome was good (no one was injured, buried or killed), it easily could have turned out much differently.  Check our observations page for a variety of reports about this avalanche.  The potential to trigger deep slabs will remain today, as over a foot of new snow combined with wind has added stress to the snowpack.  While the precip has backed off in intensity since yesterday afternoon, the snowpack needs time to adjust to its newest load.  While time will help to diminish the likelihood of triggering these deep slabs, it will not erase it.  The consequences of triggering a deep slab avalanche are severe.  Conservative terrain choices combined with safe travel practices will be essential in avoiding this problem today.

Secondary Concern

While 15" of snow is a significant load on an already stressed snowpack, 1.5" of water weight is even more significant.  If we were to get the same amount of snow with, say, a quarter inch of water, the stress placed on the underlying layers would be much less significant.  Any time I see an inch of water or more of accumulation in a 24 hour period I pay attention.  Expect to find areas with greater accumulation, particularly above treeline and in wind loaded starting zones today.  While the sensitivity of these slabs will be on the decline, do not rule out the possibility of layers within this new snow to release and produce avalanches.  The greater problem arises when this new snow slides and brings out weaknesses deeper down into the base of the snowpack.

Mountain Weather

The past 10 days has added a lot of weight and stress to our snowpack, as evidenced here by our friends at Alyeska resort.  While there have been brief moments of reprieve, the faucet turned back on yesterday with Turnagain Pass picking up 15" of new snow with 1.5" of water.  At the Sunburst station, winds have averaged 32 mph out of the E with gusts to 80.  Temps at 3800' have been in the 20s F, with freezing levels hovering around 500'.
Today expect lingering snow showers with up to 4" of new snow possible.  Winds will be out of the E and SE at 20-30 mph and temps at 1000' will be around 30 F.
The extended outlook calls for a continuation of unsettled weather, with the next significant chance for snow on Saturday afternoon.


Kevin will issue the next advisory on Saturday, January 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: Apr 28, 2017 )

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.

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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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