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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, March 30th 2015
Created: Mar 30th 6:45 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.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
0 NO RATING Below Treeline / Below 1,000'
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Our new observations page is up and running.  The new format makes it easier to submit information.  Observations from the field are the backbone of the advisory and help us to provide the most accurate information possible.  Any info is welcome and it doesn't need to be perfect!  Thanks to everyone that has submitted so far this season.


The Bottom Line

MODERATE avalanche danger exists on steep slopes in both the Alpine and Treeline elevations today.  Slabs up to 18” thick and wet loose avalanches could be triggered on slopes approaching 40 degrees and higher.  Warming temperatures in the lower elevations and occasional sunshine will increase the chances of triggering avalanches.  Cornices have grown steadily over the last week and require awareness and avoidance.


Primary Concern

Snowfall amounts over the past several days have varied across the forecast zone.  The result is slabs ranging anywhere from 6-18” in the Alpine.  On East, South and West aspects these slabs sit on a thin crust.  Yesterday my partner and I found these slabs to be well bonded to these crusts.  Traveling along areas that were being actively loaded by wind showed no signs of instability (collapsing or cracking).  Despite these encouraging results, there has been enough loading (close to 1” H20 in the Girdwood Valley) to create instability today.  It will be important to be on the lookout for upside down slabs in the Alpine.  Most suspect will be steep slopes receiving direct sunlight.

New snow in the Alpine is generally well bonded to underlying surfaces.  Caution is still advised in terrain approaching 40 degrees as new slabs need some time to adjust. photo:Wagner

Rocky Knob Sunburst

 


Secondary Concern

While we should see mostly cloudy skies today, the sun could make an occasional appearance.  If and when this happens, expect wet loose avalanches to quickly occur on terrain 40 degrees and over.  Volume will be low to medium.  Consequences will increase in line with the terrain.  Sustained steep slopes will produce more dangerous, higher volume wet loose avalanches.  If the sun pops out or the snow at your feet is wet and heavy (likely in the Treeline elevations) it will be time to back off of steep terrain.


Additional Concern

Large unsupported masses of snow are looming over many starting zones in the Alpine.  Practice good habits around cornices.  On the way up pick routes that minimize time spent in the line of fire.  On ridges and above starting zones keep your distance from the edge until you can see the base of the cornice and where it connects to the underlying terrain.


Mountain Weather

Southerly flow caused by a large complex Low pressure system in the Gulf has continued to dominate the weather pattern over the last several days.  This has resulted in mild temps with showery precipitation and moderate winds.  The Girdwood Valley picked up 6” of dense snow (.9” H20) and the Turnagain Pass SNOTEL picked up 2”/.2 (snow/H20).  Higher amounts fell on the North end of Turnagain Pass.

Today that Southerly flow will continue to bring light amounts of snow and rain with only 1-2” of snow expected.  Rain/snow line should climb as high as 1,500’.  Winds will be in the 10-15 mph range out of the East and temperatures at 1,000’ will rise into the high 30s F.

The extended outlook is showing more of the same as we move into the work week.  Circulation around the aforementioned system in the Gulf will bring multiple rounds of precip, clouds and mild temps through at least Wednesday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 30 2/rain .2 60
Summit Lake (1400') 33 0 0 10
Alyeska Mid (1700') 33  6/rain .9 37

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 24 ENE 17 39
Seattle Ridge(2400') 27 n/a 15 31

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 26, 2015 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedConditions do not look promising for a snowmachine season on the CNF this winter.... A first ever so far as we can tell. There is still a small glimmer of hope for a cold April storm but we are not holding our breath.
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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