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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, March 9th 2015
Created: Mar 9th 6:46 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'
 Show the Complete North American Avalanche Danger Scale
Special Announcement

Several close calls resulting in burials and rescues happened on Hatcher Pass yesterday.  Please visit hatcherpassavalanchecenter.org if you are planning on heading up there.  Dangerous conditions will likely continue at Hatcher Pass today.


The Bottom Line

The danger is MODERATE on steep wind loaded slopes in the Alpine.  Wind slabs up to 1 foot in depth could be triggered by skiers and riders on a variety of aspects and be large enough to injure or bury a person.  Loose snow avalanches could also be triggered in steep terrain sheltered from recent winds.

The danger is LOW in the treeline elevations, where avalanches are unlikely.


Primary Concern

Winds yesterday out of the South and West loaded slopes that don’t typically get loaded.  Yesterday my partner and I watched this loading as it happened.  Some areas were sheltered enough by surrounding terrain which prevented this from occurring.  What this means is that there are now 1-2 day old wind slabs up to a foot in depth on a variety of aspects.  On Turnagain Pass steep upper elevation North and East facing terrain is suspect.  In the Girdwood Valley one large natural avalanche released over the weekend as a result of recent winds on a Southeast aspect.  Winds will continue generally out of the Northwest today in the 20 mph range, helping to slightly increase the size and sensitivity of slabs.

Cardinal directions aside, it is more important to be able to recognize wind loaded slopes before you are on them.  Snow that looks pillowy, feels stiff or sounds hollow should be approached with caution in steep terrain.  Shooting cracks and collapsing are sure signs that the snow is unstable.  Probing with a ski pole, hand pits, and feeling with your skis or board will allow you to assess the snow below your feet.  Avoidance of terrain over 35 degrees with recent wind loading will be important today.

West winds loading East aspects along Seattle Ridge March 8, 2015

wind loading Seattle ridge


Secondary Concern

Areas sheltered from the winds will be holding 3-8” of low density snow.  On sustained slopes over 40 degrees, expect human triggered sluffing to occur.  These sluffs should be low to medium volume and large enough to knock a person over.  This problem becomes more pronounced when traveling above terrain traps such as gullies, cliff bands or trees.


Mountain Weather

Clear, cold and windy sums up the weather over the past 24 hours.  Cold air moved in behind the system that left new snow throughout the region.  Winds yesterday were strong and blowing out of unusual directions (see video).  Clouds moved in late in the day and left a skiff of new snow.

Today expect similar conditions.  Ridgetop temperatures will be in the single digits F.   Winds will be out of the Northwest at 15-20mph.  Thin clouds and light flurries this morning will give way to clearing skies by the afternoon.

Clear skies and cool temps are on tap for the first half of the week as high pressure gradually sets up over Southcentral Alaska.  Winds should diminish after today.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 17 0 0 44
Summit Lake (1400') 17 0 0 9
Alyeska Mid (1700') 19 0 0 28

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 7 WNW 9 41
Seattle Ridge(2400') 12 W 19 53

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 15, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
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.


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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