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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, December 11th 2018 7:00 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE above 2500’ in the Alpine. Watch for wind slabs in steep, wind-loaded start zones. Triggering a slab avalanche is still possible. As new snow accumulates assess how well it bonds to the snow surface below.  Pay attention to changing conditions. 

SUMMIT LAKE:  A weak and shallow snowpack exists under the recent storm snow. Slab avalanches 1-2' deep may to be easy to trigger on steeper slopes.

 


 Show the Complete North American Avalanche Danger Scale
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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Special Announcement

If you are heading to Hatcher Pass make sure to check out the Hatcher Pass Avalanche Center's forecast update and the latest observations about the human triggered avalanches that occurred Sunday.

Looking for avalanche courses or evening presentations? Check out our calendar page! There are two CNFAIC evening discussions coming up - these are FREE and a great way to get your head back in the avalanche game. This week - 'Tales from the Pit' at Blue & Gold Boardshop in Anchorage!


Avalanche Problem 1

Wind Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Leeward, steep, unsupported slopes above 2500' may still harbor wind slabs today from the winds Sunday night/Monday morning. Look and feel for stiff, pillowed snow and cracking and listen for hollow, drum-like sounds. Loading patterns can be very localized and it may be hard to tell where the wind effect is with the few inches that fell yesterday and overnight. Another 2-5" is forecast to fall today. 

Additionally, pay attention to how new snow falling today bonds to the snow below. As the inches slowly stack up over the hard wind-blown snow surface or over the melt-freeze crust at lower elevations loose snow avalanches may be a possibility in steep terrain. If the snow is cohesive enough shallow storm slabs may form. Hand pits and small tests slopes will be useful ways to assess bonding.  

Wind effect in Tincan Common, 12-9-18


Additional Concern

Persistent Slabs

As is often the case we are concerned with the snowpack in the periphery zones of our advisory area, Crow Pass and Summit Lake.  Where the Alpine snowpack is shallower, the potential to trigger a persistent slab avalanche on weak snow near the ground increases. Observations prior to the storm showed weak facets near the ground in Summit Lake. We have limited information from north of Girdwood but suspect a weak set-up.  If traveling to these areas the possibility of triggering a dangerous avalanche remains. Choose terrain carefully.

 

Red flags to watch for:

  • Recent avalanches 
  • Whumpfing (collapsing) of the snowpack, a sign to avoid avalanche terrain.
  • Shooting cracks, likely to be seen near ridgelines where the wind has formed wind slabs.

Tenderfoot, 12-5-18 


Mountain Weather

Yesterday: Skies were cloudy with snow showers throughout the day. Temperatures were in the 20Fs to low 30Fs. Winds were easterly 5-15 mph with gusts into the 30s. Snow showers continued overnight, winds were light and temperatures dropped a few degrees. 

Today: Snow showers continue with 2-5" forecast to fall today with an additional 2-6" tonight. Temperatures will start in the mid to high 20Fs and drop slowly throughout the day into the low 20Fs and teens tonight. Winds will be variable and light. 

Tomorrow: Snow showers and cooler temperatures are the trend for the week. Thursday may see a brief window of clearing. The pattern remains active into the weekend. Stay tuned as we watch storm tracks and temperatures! 

*Seattle Ridge anemometer (wind sensor) is rimed over and not reporting. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  29    0.4   29 
Summit Lake (1400')  27    1   0.1 
Alyeska Mid (1700') 28  0.3  12

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 21   NE  36
Seattle Ridge(2400') 25  *no data  *no data   *no data  

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: May 06, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of 4.3.19
Placer River: ClosedClosed as of 3.20.19 due to lack of snow.
Skookum Drainage: ClosedPlacer access closed as of 3.20.19 due to lack of snow.
Turnagain Pass: ClosedClosed as of 5/6. Thanks for a great season all, see you next winter!
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Closed
Lost Lake Trail: ClosedClosed as of 3.22.19 due to lack of snow
Primrose Trail: ClosedClosed as of 4.3.19 due to lack of snow
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: ClosedClose as of 5.1.2019
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
Summit Lake: Closed

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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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