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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   CNFAIC Staff  
Friday, December 25th 2015
Created: Dec 25th 4:08 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.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
 Show the Complete North American Avalanche Danger Scale
TOTE Maritime
Special Announcement

Deck the hills with wind and snow, Fa la la la la la la la!

The Xmas question… When will avalanches start to go? Fa la la la la la la la!

Don we now our winter apparel, Fa la la la la la la la!

Riders sing a powder carol, Fa la la la la la la la!

Please be safe and heed the warnings, Fa la la la la la la la!

The Xmas holiday will be stormy, Fa la la la la la la la!

 

Happy Holidays from the CNFAIC crew! 


The Bottom Line

The avalanche danger will increase to CONSIDERABLE today as a strong winter storm impacts the advisory area. Periods of heavy snow combined with wind are forecasted. The new snow will land on a weak snow surface in most of the terrain. The hazard could increase quickly. Human triggered avalanches will be likely and natural avalanches will be possible. Caution is advised as conditions change. The danger may go to HIGH by the evening.


Primary Concern

A winter storm warning is in effect for the region today. If the forecasted snow totals verify we could quickly start to have storm snow concerns. Initially we could see loose snow avalanches. The new snow will land on weak snow. Surface hoar and near surface facets have formed during the past few days on all aspects and elevations. These could become a very reactive weak layer as the new snow piles up. Winds have destroyed the surface hoar in some areas in the Alpine but unfortunately we will not have x-ray vision to determine exact distribution. The winds have already started to pick up this morning. This combined with the new snow could rapidly create sensitive slabs. Pay close attention to changing conditions. Watch for heavy precipitation intensity, strong winds, shooting cracks and whumpfing. Low visibility will make it hard to see what is above you. Avoid travel in runout zones. If you do venture out today conservative terrain choices are advised. 

Yesterday's snow surface = Today's weak layer. 

 


Secondary Concern

The weak snow that formed in early December sitting over the Thanksgiving Rain Crust or old hard snow is now buried under 2-4' of snow. This combination has been the cause for concern and heightened caution in the backcountry for the past week. This setup could now become overloaded with the additional weight of new snow and wind loading. If avalanches step down into this layer, they could be quite large and destructive. 


Additional Concern

There have been cornice triggered avalanches during the past week and there are looming sections overhanging slopes today. Cornices will grow quickly with the new snow and may be triggered by the increasing winds. Visibility may make it challenging to see what is above. This is an added reason to stay away from runout zones.


Mountain Weather

Yesterday was clear in the morning with increasing clouds throughout the day. Winds were light and shifted from W to E. Temperatures were in the single digits in the valleys and the mid-teens at ridge tops.

The winds have picked up this morning and temperatures are warming as the weather system approaches.

NWS Zone Forecast for Turnagain:

...WINTER STORM WARNING FOR HEAVY SNOW REMAINS IN EFFECT FROM
9 AM THIS MORNING TO 6 AM AKST SATURDAY...

* SNOW...13 TO 26 INCHES...HIGHEST AMOUNTS THROUGH TURNAGAIN PASS AND
NEAR GIRDWOOD.

* VISIBILITY...NEAR ZERO AT TIMES IN HEAVY SNOW AND BLOWING SNOW.

* WIND...EAST WIND 10 TO 25 MPH EXCEPT EAST 40 TO 55 MPH THROUGH
PORTAGE VALLEY AND TURNAGAIN ARM...STRONGEST WINDS THIS
EVENING.

* TIMING...SNOW WILL DEVELOP THIS MORNING THEN BECOME HEAVY THIS
AFTERNOON. HEAVY SNOW WILL CONTINUE THROUGH TONIGHT FOR INLAND
AREAS BEFORE DIMINISHING EARLY SATURDAY MORNING. LOCATIONS ALONG
THE COAST WILL CHANGE TO RAIN LATE THIS AFTERNOON OR EVENING
RESULTING IN LESS SNOW ACCUMULATION OVERALL. The rain/snow line is expected to rise to 500' tonight.

The storm continues into tomorrow with snow/rain showers and easterly winds. Temperatures will be in the high 20Fs to mid 30Fs.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 15   0 49 
Summit Lake (1400') 10   0 0  17
Alyeska Mid (1700') 15  0  0 35 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 14  ESE  15 
Seattle Ridge(2400') 14 ESE  10 14 

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 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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
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