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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Sunday, December 13th 2015
Created: Dec 13th 5:45 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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Silverton Mountain Guides
Special Announcement

Today, Sunday December 13th, the Chugach National Forest has opened Turnagain Pass to motorized use. Scroll to the bottom of this page for more information on other riding areas in the Chugach National Forest.  If you head out, please ensure everyone in your group is carrying avalanche rescue gear and knows how to use it! 

CNFAIC is hosting a Free Avalanche Rescue Workshop on Sunday, December 20th at Turnagain Pass. This is a great opportunity to practice beacon searches, learn strategic shoveling techniques and meet local forecasters! This workshop is open to everyone and anyone, novices and experts. We encourage all user types to participate – snowmachiners, skiers, boarders, kicker-builders, etc… 


The Bottom Line

The avalanche danger is CONSIDERABLE both in the Alpine and at Treeline elevations where a 2-3’ thick slab is sitting on various layers of weak snow. Today is the perfect recipe for an avalanche accident—it is the opening day of snowmachining in Turnagain Pass plus clear skies following a big storm.  Lots of people are anticipated to hit the slopes today. It is EXTRA important to not group up under large slopes, travel one at a time, and tread lightly. 

Below Treeline there is a MODERATE avalanche danger.  The new snow is showing signs of good bonding; though keep in mind we are still within 48 hours of a storm, and if an avalanche was triggered from above it could run into this elevation band. 

*A Blizzard Warning has been issued by the National Weather Service starting at 6pm this evening through Portage Valley and Turnagain Arm. Avalanche danger will likely be increasing after dark with increasing winds and snowfall. Watch for deteriorating conditions in the afternoon and give yourself plenty of time to return home safely. 

 


Primary Concern

A storm that lasted three days left an upwards of 20+” of new snow in the mid and upper elevations of Turnagain Pass. This storm favored the Northern side of Turnagain including Eddies, Tincan and Seattle Ridge. Strong sustained Northeast winds accompanied this storm with one reported avalanche on Tincan that likely occurred near the end of the storm. Little information exists in the Alpine elevations due to dangerous avalanche conditions and limited visibility.  

This new snow is sitting on top of various weak layers of old snow, which are resting on a uniform bed surface. Yesterday test pit results confirm this structure has potential to be reactive and propagate. If the right trigger were to collapse a weak layer it will likely cause a large avalanche. Traveling on or under large steep slopes should be avoided until the snowpack has more time to adjust.

If you are planning to participate in the first day of snowmachining for the season, don’t be deceived by drastically different snow conditions as you head North and start to gain elevation. Be aware of others and do not congregate underneath large open slopes like Repeat Offender on the Seattle Ridge up-track. The only way to manage this challenging avalanche problem is by minimizing your exposure to steep slopes and practicing safe travel rituals.

Early Season Sledding Reminders:

  • Check your partner’s beacon and equipment at the parking lot
  • Make sure you have a shovel and probe on your body
  • Be aware of early season hazards like drainages with open water
  • Minimize your impact in areas with thin snow coverage like ‘Rookie Hill’

Secondary Concern

Winds are expected to increase in the afternoon, and could be in the 30's mph with gusts in the 40's mph. There is a lot of snow available for transport and lots of potential to form new wind slabs. Luckily the timing is expected to be later in the day, but pay attention for drifting snow, shooting cracks, and wumpfing sounds - all Redflag warnings that the snow is not safe. 


Additional Concern

 

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED A BLIZZARD
WARNING...WHICH IS IN EFFECT FROM 6 PM THIS EVENING TO 6 AM AKST
MONDAY.

* LOCATION...PORTAGE VALLEY AND TURNAGAIN ARM.

* SNOW...3 TO 6 INCHES.

* VISIBILITY...REDUCED TO LESS THAN ONE QUARTER MILE AT TIMES.

* WIND...EAST WIND 20 TO 30 MPH INCREASING TO 25 TO 40 MPH AFTER
         MIDNIGHT.

* TIMING...BLIZZARD CONDITIONS WILL START THIS EVENING AND BECOME
  MORE INTENSE AFTER MIDNIGHT. CONDITIONS ARE EXPECTED TO IMPROVE
  EARLY MONDAY MORNING.

Mountain Weather

A storm ended yesterday morning leaving overcast conditions throughout the day. Temperatures started to fall into the mid to low 20’s F, and ridgetop winds were light from the Northeast. Overnight temps continued to drop into the mid teens F.

Today skies are expected to be sunny in the morning becoming cloudy by the afternoon. Temperatures will be in the 20F’s with ridgetop winds from the Northeast, 15-25 mph. Winds and snowfall are expected to intensify by early evening and the National Weather Service has issued a Blizzard Warning starting at 6pm tonight. 

 A very large low has been deepening over the Bering Sea and is expected to move into Southcentral Alaska tonight and last through Monday morning.



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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 21  36 
Summit Lake (1400') 19  13 
Alyeska Mid (1700') 23  trace  0.2   31.5

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 15  NE 11 
Seattle Ridge(2400') 17 

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 25, 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

Subscribe to the Turnagain Area Avalanche Advisory:

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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
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