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Avalanche Advisory

Turnagain Area Avalanche Advisory
Sunday, November 25th 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

A powerful storm moving through is expected to increase the avalanche danger to HIGH in the upper elevations today. Over 1' and up to 2' of snow accumulating by this afternoon should cause natural avalanches to occur. Warming temperatures will also increase the likelihood of avalanche activity at these high elevations and bring rain to 2,200'. The avalanche danger is CONSIDERABLE in the treeline band as avalanches from above may run into these mid-elevations. Travel above treeline is NOT recommended.


 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.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
Avalanche Problem 1

Storm Slabs

Almost Certain
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Chance

Historic
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CHANGING WEATHER AND INCREASING AVALANCHE DANGER

A warm, wet and windy storm is over the region currently. Roughly 10 to 12" of snow has fallen in the Alpine zones with another 10 to 14" expected today (above 2,500'). At the mid-elevations, roughly 6 to 10" of wet snow has fallen with an additional 1" of rain (yes rain) expected up to 2,200' this afternoon. Easterly ridgetop winds will continue to be in the 20's with gusts in the 50's mph. 

Although there was bare ground before this storm up to 2,000', above this a shallow snowpack has been forming (see photos below). Rain last weekend followed by cool temperatures formed a crust up to the ridgetops on this pre-existing snow surface. The kicker is, surface hoar formed on the crust before it was buried yesterday. So, what we have is a perfect recipe for avalanche activity in the upper elevationsAny new snow accumulation is expected to slide off the old snow surface easily. How much avalanche activity we will have and how big those avalanches will be is directly related to how much snow falls. As of this morning, there is roughly a foot of snow from yesterday and another foot expected today - again, this is all above 2,500'. Therefore, storm slabs up to 2' thick are possible and where winds have been loading up to 3 to 4+' thick. 

Snow falling along the road and up to ~2,200' is expected to turn to rain by this afternoon. This will saturate and melt much of the 6 to 10" of wet snow existing in these mid-elevations (1,000' to 2,500'). The worry at these elevations is being in the runout zone of an avalanche from above where debris can run. All this said, today is a day to leave the mountains alone and look ahead to the cooler weather on tap for the middle part of the week! 

 

 

Sunburst, above the alders - hard snow with suspected surface hoar on top existed before this storm rolled in yesterday (Saturday)

 

 

The pre-existing snow line was a little lower on Tincan, just above1500'

 

East facing slopes of Repeat Offender on Seattle Ridge on Friday, November 23. Snowline was around 2000'.

 

Looking into Lynx Creek drainage, Northern aspects before the storm on Friday.


Mountain Weather

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 31  13 
Summit Lake (1400') 31  1 0.2
Alyeska Mid (1700') 31  0.5 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 25  NE  21  46 
Seattle Ridge(2400') 30  11  33 

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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