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Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, December 8th 2018 7:00 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

Travel is not recommended in avalanche terrain again today as a HIGH avalanche danger remains. Large natural avalanches are likely in the upper elevations as snowfall and winds continue. Wet avalanches are likely in the mid elevations and in channeled terrain below treeline.

PORTAGE:  Up to 5’ of snow has fallen in the high elevations, avalanches are still likely to run their full length to valley bottoms. Avoid being in avalanche paths.

SUMMIT LAKE:  A very weak and shallow snowpack exists under the storm snow. Slab avalanches 1+’ deep will be very easy to trigger and may release naturally on steeper slopes.


 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
Special Announcement
  • 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. 

Avalanche Problem 1

Storm Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Yesterday's quick moving and powerful storm brought feet of snow to the Alpine, inches of rain to sea level and 90mph winds to the ridgetops. The rain snow line bounced between 1,000' and 1,500' in most areas. Mostly wet snow and rain fell along Turnagain Pass and as of this morning, there is what looks to be an inch or two of snow surviving along the Pass. Rain and snowfall have decreased overnight but are on tap to pick up slightly again this evening. 

Storm totals at the mid-elevation snow stations (beginning Thursday night to 6am this morning)

  • Turnagain Pass at 1,880':  1.5-2" of water equivalent, roughly 1.5-2' of snow above treeline
  • Girdwood Valley at 1,700':  2.7" of water equivalent, roughly 2-3' above treeline
  • Summit Lake at 1,400': 0.7" of water equivalent (rain/snow mix along the road at Summit Pass), roughly 6-8" of snow above treeline

Widespread avalanche activity was seen yesterday. Debris piles were observed running into snow free zones below 1,000' in Girdwood and Portage Valleys as well as Seward. Although natural activity will be expected to decrease today, the mountains are still in shock and large avalanches are still likely in many areas. With additional snowfall tonight, natural avalanche likelihood could increase again. That said, today is another day to avoid avalanche terrain all together.  

Moose Mountain avalanches, outline of debris marked in orange. This is near MP 52 along the Seward Highway (Summit zone). Photo: Alex McLain

 

 

Upper Girdwood Valley, North side of Crow Creek Valley. Debris from avalanches above running to valley floor.

 

Seward's Mt. Benson with several large debris piles from avalanche activity higher on the mountain. Photo: Jamie Lyons

 

Just enough snow to make it white along Turnagain Pass yesterday. This is Rookie Hill in the foreground looking at the base of Seattle Ridge, seen from the motorized parking lot. Photo: Will Brennen


Mountain Weather

Yesterday:  Heavy rain below 1,000' and heavy snowfall above 1,500' - a wintery mix in between these elevations. Snow and water totals above and below. Winds were strong out of the East, averaging in the 60's mph with gusts into the 90's. Temperatures were in the upper 20's along the ridgetops and mid 30's at 1,000'. 

Today:  Rain and snowfall has decreased overnight. Scattered showers should be seen around the region today and could pick up slightly tonight. Between .2-.3" of rain below 1,000' is forecast with 2-4" of additional snow at the higher elevations today. Tonight snow line should lower and an additional 3-5" of snow could be seen near sea level by tomorrow morning.  Ridgetop winds will continue from the east in the 25-30 mph range. Temperatures will be in the low 30's at 1,000' and mid 20's along ridgelines through the day. 

Tomorrow:   Snowfall making its way to sea level will hopefully greet us in the morning as snow lines are forecast to lower. Snowfall should taper off by tomorrow morning bringing a break in storms before yet another wave of snow (and possibly rain at sea level) ushers in later on Sunday. Stay tuned!


*Seattle Ridge anemometer (wind sensor) reading uncommon wind direction during height of storm yesterday. Sensor is now rimed back over. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 33  14  30 
Summit Lake (1400') 34  0.4 
Alyeska Mid (1700') 33  1.92

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 26  NE  41  98! 
Seattle Ridge(2400') 30  *WNW *25 66 

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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