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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Friday, March 15th 2013
Created: Mar 15th 5:49 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 generally LOW today.  The hazard is MODERATE in areas above treeline where snowmachine and skier triggered avalanches are possible.  Storm snow issues in the form of wind slabs and loose snow avalanches are the main concerns in the higher elevations.  Cornices are also a threat in the mountains today.


Primary Concern

It is always good to remember what happened in the past.  Three nights of calm, clear and cold weather earlier this week helped to form weak snow (surface hoar and facets) at the surface.  That weak snow is now blanketed with a fresh coat of paint, and that paint will be easy to peel off today, especially above treeline.  Wind slabs will be easiest to trigger today in upper elevation starting zones.  These newly formed slabs are sitting on a variety of weak interfaces, including surface hoar on the northern half of the compass and weak faceted snow on the southern half.  Look for these slabs to be in the 12" range and be very sensitive to the weight of a person or sled.  Slabs unaffected by wind will also be something to look out for and will be smaller, in the 6-8" range.  Today will be a good day to ratchet back your terrain choices, as those big lines that got hit on the last clear day now have the perfect slab/weak layer combination for avalanche activity.


Secondary Concern

This last batch of moisture that refreshed the snow surface ended with very light winds.  This should make for excellent riding and skiing conditions but also make loose snow avalanches a problem to deal with.  Volume should be in the low to moderate range and should be fast moving on steep shaded slopes in the higher elevations.  Sun and warming will create the possibility of sluffs to be more damp on sunlit aspects through the day.  Pay attention to loose snow moving downhill with you and move away from it, especially above terrain traps such as cliff bands, gullies and trees.

Additional Concern
Cornices
We have seen several very large cornices drop in the past few weeks.  This problem is pretty simple to deal with; minimize your time near and especially below cornices, as they have the potential to do a lot of damage as evidenced last week in the Goldpan area on Turnagain Pass.


Mountain Weather

In the past 24 hours the mountains around Turnagain Pass have picked up 6" of new snow/.4" of water with lesser amounts in the Girdwood Valley and south towards Summit Lake.  Winds at the Sunburst station at 3,880' have averaged 13mph out of the East with gusts to 45mph.  Temperatures have remained cool with sea level stations staying in the mid 20s F and ridgetops in the teens.

Today expect periods of clear skies as we are between two weak low pressure systems.  No precipitation is forecasted.  Winds will be very light out of the East at 5mph and temperatures will be in the high 20s F at 1,000'.

The extended outlook calls for a mix of sun and clouds over the next several days with no precipitation expected.

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Kevin will issue the next advisory tomorrow morning, March 16th.

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.

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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
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