Thursday, December 4th 2014 5:46 am by Wendy Wagner
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
The avalanche danger is expected to rise to MODERATE today in the Alpine terrain as 3-5" of new snow is forecast accompanied by moderate Easterly winds. In areas with new snow and wind, fresh wind slabs 6-10" in depth will be possible to trigger on leeward slopes off ridgelines and other exposed terrain features. Loose snow sluffs on steep slopes should also be expected in areas seeing new snow. A continued lack of snow cover below treeline results in no rating at this low elevation.
In the event only a trace of new snow falls, watch for old wind slabs in steep exposed terrain. Otherwise, triggering an avalanche will be unlikely.
|Show the Complete North American Avalanche Danger Scale|
|Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.|
|Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.|
There is uncertainty as to how much new snow the Eastern Turnagain Arm will see today. Likely, some areas will get several inches while a couple ridgelines over may see only a trace. In areas seeing several inches or more of new snow, fresh wind slab avalanches will be the main concern. The winds are forecast to average between 15-25mph, which are ideal wind loading speeds. The Seattle Ridge weather station is reading in this range this morning while the Sunburst weather station is quieter (~10mph) with speeds increasing through the day.
The good news is, the warm temperatures (mid 20's F) above treeline will help to stabilize the new snow relatively quickly. Your best bet at triggering an avalanche is to step on a very fresh wind loaded slope. Watch for wind loading in action and areas where the snow is more cohesive and cracking around you. These slabs should be in the 5-10" range and fairly soft.
Below is a look at yesterday's surface. This area, in the Summit Lake region, is quite wind affected, however many areas still harbor soft settled powder.
Dry snow sluffs at the upper elevations are possible while wet, or moist, snow sluffs are possible near treeline. Temperatures look to climb to 32F near treeline, which will moisten any new snow that falls. These should be low volume and something to keep in mind on steep slopes over 40 degrees.
Weather yesterday was mostly cloudy with light to moderate Easterly winds. A trace of snow was picked up at Turnagain Pass with the rain/snow line near sea level. Overnight, temperatures have warmed a few degrees to the mid 20'sF on the ridgetops and 30F at treeline. This is associated with a large scale Southeasterly flow that is pumping warm air our way from the South.
Today, we are expecting a pulse of moisture embedded in the Southerly flow to add 3-5" of new snow with slightly warming temperatures (up to 32F at treeline and the upper 20'sF on the ridgetops). Rain (and maybe a rain/snow mix) is expected at sea level. Winds should remain 15-25mph from the East.
This general pattern is expected to continue into the weekend with off-and-on snow showers above 1,000' and rain below - amounts of snow are uncertain but look to be only a few inches here and there. We could see a break in cloud cover and precipitation tomorrow, Friday.
PRECIPITATION 24-hour data (6am - 6am)
|Temp Avg (F)||Snow (in)||Water (in)||Snow Depth (in)|
|Center Ridge (1880')||28||1||0.1||19|
|Summit Lake (1400')||24||0||0||5|
|Alyeska Mid (1700')||29||1||0.1||17|
RIDGETOP 24-hour data (6am - 6am)
|Temp Avg (F)||Wind Dir||Wind Avg (mph)||Wind Gust (mph)|
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).
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, 2018 )
|AREA||STATUS||WEATHER AND RIDING CONDITIONS|
|Johnson Pass:||Closed||Closed as of April 20th|
|Placer River:||Closed||Closed as of April 17th|
|Skookum Drainage:||Closed||Closed as of April 1st.|
|Turnagain Pass:||Closed||Closed as of May 7th. Happy summer, see ya when the snow flies!|
|Twentymile:||Closed||Closed as of April 13th|
|Carter Lake:||Closed||Closed as of 4/27|
|Lost Lake Trail:||Closed||Closed as of April 13th|
|Primrose Trail:||Closed||Closed as of April 13th|
|Resurrection Pass Trail:||Closed||Closed as of April 20th|
|Snug Harbor:||Closed||Closed as of 4/27|
|South Fork Snow River Corridor:||Closed||Closed as of April 13th|
|Summit Lake:||Closed||Closed as of April 20th|
SNOW AND AVALANCHE HOTLINE (907) 754-2369
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