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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Tuesday, December 6th 2016
Created: Dec 6th 4:43 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

Interested in forecasting snow/weather conditions for your day in the backcountry, or your weekend trip? Join CNFAIC forecaster Wendy Wagner TONIGHT for a FREE mountain weather talk at Ski AK in Anchorage - 6:30-8pm!!

Planning on taking an avalanche class? The Friends of the CNFAIC is offering two avalanche scholarships through the Rob Hammel fund. Both scholarships are for $500. One is for avalanche professionals and the other is open to anyone!  The deadline for both scholarships is Dec 15th! For more information click this link HERE


The Bottom Line

Today the avalanche danger is MODERATE in the alpine where trigging a fresh wind slab up to 1’ thick will be the most tender on steep leeward terrain features. Triggering a larger slab avalanche 1-2+' thick is also possible on all aspects and the likelihood goes up as one travels to steeper slopes that have had less traffic this season. Evaluate snow and terrain carefully and manage your terrain choices with safe travel protocols.

Below 2000' in the trees where the snow is loose and unconsolidated the avalance danger remains LOW.

If headed to Summit Lake check out the Summit Lake Summary HERE and a recent observation from Fresno Ridge on Sunday, Dec.4, HERE.


Primary Concern

Yesterday Easterly ridgetop winds were transporting snow and loading Western aspects in the afternoon and overnight. With about 6-8” of snow available for transport, fresh wind slabs, up to 1ft thick could be tender today. Expect wind slabs to be extra touchy in rocky areas where the snowpack is thin and weak. This wind stiffened snow could also be adding stress to the Nov.16 layer of buried surface hoar where a slab up to 2’ thick could be enough to bury someone. Pillow-shaped snow on steep convexities and cross-loaded gullies will have more potential for this higher consequence avalanche. Today’s winds are expected to decrease this morning, but should you see activily loading snow or shooting cracks - these are obvious clues the snow is unstable.

Old ski tracks filled in quickly yesterday afternoon on a Western aspect on Tincan. Top of the ridge in this picture is 3600'. 


Secondary Concern

If you have been reading our advisories over the last few weeks then you are probably well aware of the Nov.16th layer of buried surface hoar. The most recent avalanche activity on this layer was reported on Saturday, Dec. 3rd on Cornbiscuit, where a group intentionally triggered a cornice on a steep Northern chute. They observed a slab 8-10” thick pull out and identified the buried surface hoar as the culprit. There are a number of complexities associated with this avalanche problem including the knowing the full extent of where this layer remains in the snowpack. Numerous small avalanches have occurred on this layer and numerous small snow storms keep covering up the evidence. Most of this activity has been on the popular Southwest slopes of Sunburst and Tincan and little is known about places less traveled. Don’t forget this layer is on all aspects and continues to show propagation potential in test pits above 2000’. The other important thing to note is the slab character is becoming denser with recent wind events, which means the slab could break above you once well onto the slope.  

Be sure to use safe travel protocols if venturing into avalanche terrain today: 

  • Expose one person at a time
  • Group up in safe zones
  • Have an escape route planned
  • Watch your partners and be aware of other groups around you

Check out the results of a test pit at 3300' on a North aspect of Tincan from yesterday, Dec.5.  


Mountain Weather

Yesterdays clear skies became overcast in the afternoon and light flurries were observed between Girdwood and Turnagain Pass. Temperatures increased throughout the day, -8F in AM to 22F by evening, along the road (1000’). Easterly ridgetop winds increased in the afternoon, 15-30mph, along ridgetops. Overnight about 2 inches of snow was recorded in Turnagain Pass and trace in Girdwood. 

Today expect scattered snow showers with an accumulation of 1-4' inches. Temperatures will likely remain in the mid to low 20F’s and winds are expected to be light from the East. 

Dry arctic air continues to keep most of Alaska under a cold air mass including parts of Southcentral Alaska. With the exception of several low pressure systems tracking through the Gulf of Alaska bringing scattered snow showers to the area, temperatures are expected to remain cold throughout the week. 



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 17   .2 22 
Summit Lake (1400') 14  .2 
Alyeska Mid (1700') 19  trace  .02  10 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 13   ENE 11  35 
Seattle Ridge(2400') 15  ESE  16  27 

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 28, 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: OpenPlacer remains open but SKOOKUM DRAINAGE will close to motorized use on April 1st.
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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