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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Saturday, February 6th 2016
Created: Feb 6th 5:19 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
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The Bottom Line

There is a CONSIDERABLE avalanche danger in the Turnagain Pass region at elevations above 1,000'. It is expected that triggering a slab avalanche 2-3'+ feet thick will be likely on slopes steeper than 30 degrees. This is due to weak snow sitting under 2-3' of new snow. Cornice falls are likely as well which could trigger a large and dangerous avalanche below. Lastly, glide avalanches are still releasing with debris running into heavily used areas. 

*These are dangerous avalanche conditions. Careful snowpack evaluation and conservative terrain selection is necessary for a safe day in the backcountry. Safer areas to recreate are on gentle slopes and/or in the flats.

**Dangerous avalanche conditions exist in the Summit Lake area as well. Please see today's Summit Lake Summary for more information. 


Primary Concern

Today could be one of those days where someone could easily be caught in an avalanche: It will be our first chance for a break in cloud cover after a 4 day storm and it's Saturday. The big concern centers around 2-3' of new snow, which fell between Tuesday and Friday, that sits on a layer of weak older snow. This weak old snow was last weekend's surface, which became loose and faceted along with a layer of surface hoar on top. Not only that, at the mid-elevations, between 2,000 and 3,000', a crust exists below the weak snow (see photo below). What this all boils down to is that the new snow may not stabilize very quickly after this storm and people could trigger large and dangerous avalanches through the weekend. Things to keep in mind with this type of snowpack:

1)  This unstable 'set-up' is one we have not seen this year

2)  Triggering an avalanche remotely, from the side, top or below a slope is possible 

3)  The snowpack between 2,000' and 3,000' (where the weak snow/crust combination exists under the new snow) could be more unstable that the higher elevations. Crusts can inhibit stability and contribute to the possibility for remote triggers.

4)  With little ground truth information at this point, very cautions terrain selection is required. 

5)  Sticking to slopes less than 30 degrees - with nothing steeper above you - to give the snowpack time to adjust is a great way to have a safe weekend in the backcountry.


The photo below shows the new snow at 2,000'. At this elevation the snow was very warm and dense; the rain snow line was just below this and lighter and deeper snow existed just above this. 


Secondary Concern

The glide avalanche cycle continues.... Another glide crack released into a full-blown avalanche sometime late on Thursday or early Friday morning. These cracks are clearly still active and avalanching. Again, this is not the type of avalanche that can be triggered, but instead release spontaneously on their own. Just one more reason to avoid being under steep slopes today.

Photo: Glide avalanche on the Southeast face of Seattle Ridge, between the motorized lot and the motorized up-track.


Additional Concern

With the warm and sticky nature of the new snow, cornices are likely to have grown even larger (they are already behemoths...) and be on the verge of collapse. These are not only hazards in themselves, but are also likely to trigger large avalanches below.


Mountain Weather

Yesterday we saw the tail end of the storm cycle move out with light snowfall adding roughly 1-3" of new snow. 1" fell at the Center Ridge SNOTEL at 1,900' while 3" fell in Girdwood Valley at the Alyeska Mid station. Winds died down as well with averages ~15mph from a generally East direction. Temperatures were warm (low 30's at 1,000') with a rain/snow line fluctuating between 1,000' and 1,200'.

This morning we are seeing a quick pulse of moisture, increasing cloud cover and increasing Easterly winds move though. This should exit the region by mid-day and skies may break up if we are lucky. We may pick up another 1-3" of snow with a rain/snow line ~500' this morning. Winds are expected to be in the 15-25mph range from the East on the ridgetops. Temperatures look to hover in the upper 20's at 1,000' and near 20F at 4,000'. 

For Sunday, another band of wind and snow looks to move in. We should see some breaks in this stormy pattern this week hover, so stay tuned.
 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 28   0.1 110 
Summit Lake (1400') 27  0.1  32 
Alyeska Mid (1700') 30  0.33  87 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 21   NE 15  46 
Seattle Ridge(2400') 25 

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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