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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Wednesday, March 4th 2015
Created: Mar 4th 6:35 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.
0 NO RATING Below Treeline / Below 1,000'
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Special Announcement

Our NEW OBSERVATION PAGE is up and running!  Please check out the new format and consider submitting a snowpack or avalanche observation on your next day in the mountains.  We are always looking for more info and photos to help paint a better picture of avalanche hazards across south central Alaska!


The Bottom Line

There is a MODERATE avalanche danger above 2,500’ where weak, faceted snow is still being found 1-2 feet below the surface and triggering a slab in steep terrain (>35 degrees) will be possible.  Careful terrain and snowpack assessment are warranted above treeline today.

The danger is LOW at Treeline and below where triggering an avalanche is unlikely.


Primary Concern

Snowpit information again yesterday points toward a layer of weak, faceted snow that is still showing signs of mischievous behavior above about 2,500’.  This is roughly where the stout and supportable melt/ freeze crust begins to thin out enough for a skiers weight to physically upset these buried facets. 

We found a high degree of variability across any given slope yesterday with unstable snow (moderate strength, high propagation potential) in one snowpit and generally stable snow just 15 feet away.  This points toward a slab that is not widely connected across slopes.  Of course snowpit data is just one small piece of the puzzle and it’s possible that someone could get away with skiing bigger, steeper lines without incident today but it is worth keeping in mind the nature of a persistent weak layer.  It often takes weeks or even months for these to heal.  The general rule for a facet is that once buried, it is not to be trusted until it’s in the River’. 

It is still important to treat steep and complex terrain with suspicion today.  Practice safe travel protocol, assess terrain before committing and minimize your exposure accordingly.  Avoid trigger points (thin spots or steep roll overs) on terrain over 35 degrees and travel one at a time on suspect slopes using islands of safety as you go.

We were finding a high degree of variability across slopes, even in snowpits this close together.  More info on the NEW OBSERVATIONS PAGE!


Mountain Weather

Yesterday saw winds diminishing and temperatures climbing throughout the day.  In the morning hours the rain snow line hovered around 600’ but by mid-afternoon that had climbed to roughly 1800’ with light rain/ snow under grey-bird skies.  

Today looks to be much of the same as we are under the influence of warm, moist southerly flow with light rain/ snow continuing at least thru the morning and tapering off this afternoon.  Rain/ snow line looks to be around 1,000’ where we may see an inch of snow accumulation throughout the day.  Ridge top winds are expected to be from the East in the 10-15mph range with temperatures in the high 20’s at 3,000’ and low to mid 30's at 1,000'

Heading into the weekend, a series of weak lows will continue to move through our area promoting a similar rain/ snow mix in south central AK. Late in the weekend (Sunday) and into next week temperatures appear to cool off enough to support all snow.

PRECIPITATION 24-hour data (6am - 6am)

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33   1  .2  41
Summit Lake (1400') 33 .02   7
Alyeska Mid (1700') 33   1 .1   25.5

 

RIDGETOP 24-hour data (6am - 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  25  ENE  11 28 
Seattle Ridge(2400') 27   n/a 17  35 

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: Mar 02, 2015 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThe CNF is in a sad state of affairs this winter in terms of motorized use. A drive over Turnagain pass in late-February looks like the monsoon season of September/ October. Though unprecedented, Rangers have not given up hope yet on a snowmachine season.... Remember March 2014??? 5 feet of snow in 5 days! This is Alaska afterall!
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: Closed
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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