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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, December 7th 2014
Created: Dec 7th 5:28 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
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Special Announcement

Yesterday evening we received a report of an avalanche accident South of Fairbanks, near milepost 205 of the Richardson Highway. Details are very limited at this time. Developing information can be followed HERE and HERE.


Upcoming FREE Avalanche Awareness talks from CNFAIC forecasters:

Tuesday Dec 9th at 6pm - REI Anchorage.  A few spots are left.  Visit the REI website to sign up.

Thursday Dec 11th at 6:30pm - Alaska Avalanche School in Anchorage.  Installment #2 of our Fireside Chat Series.  This evening's topic will be "Avalanche Basics and Rescue Fundamentals".


The Bottom Line

The avalanche danger will rise to MODERATE today at all elevations above 1,500'. Below 1,500', little to no snow cover results in no rating. Wet snow avalanches will be possible to trigger near treeline in areas with rain falling on snow. These wet avalanches are expected to be heavy and dense sluffs that can be initiated on slopes over 35 degrees and on all aspects. At elevations above treeline, where 6-10" of snow is expected to fall, wind slab avalanches will be the main concern due to strong winds loading leeward slopes.

*The avalanche danger may rise to CONSIDERABLE in areas seeing significant precipitation (over an inch of rain through the day). These areas are on the periphery of the forecast zone, such as Portage Valley and Whittier.

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The next advisory will be Tuesday Dec 9th at 7am.

Avalanche Outlook for Monday: Expect similar avalanche conditions for Monday. With continued rain to treeline a MODERATE danger for wet avalanches is likely to remain at the treeline elevation. Above treeline, another 3-5" of snow is expected with moderate to strong winds which will keep wind slab avalanches a concern.


Primary Concern

It is the dreaded rain-on-snow that is in our future today, and into the early part of the week. With climbing temperatures overnight and periods of heavy rain expected at sea level, the question is, "How high will the rain get?" The answer is, 1,200' for sure, likely 1,500' at times and possibly a bit higher. 

Wet loose snow avalanches will be the most likely type of wet avalanche to be triggered. These can entrain significant amounts of heavy dense snow if the slope is sustained and steep enough (> 35 degrees). If you are getting out today, watch for areas where the snow is becoming saturated and heavy. Steering clear of steep saturated slopes will be good ways to avoid a wet sluff. Also, keep in mind terrain traps, such as steep narrow gullies in the Tincan Trees. These steep walled and narrow terrain features can pose a threat if even a small amount of heavy snow slides down onto you.


Secondary Concern

In the Alpine terrain, above treeline, we are expecting around 6-10" of wet to moist snow to fall. Along with this, winds are forecast to be strong from the East and Northeast which will quickly form wind slabs, drifts and cornices. The warm nature of the new snow will allow it to bond rather quickly to the preexisting surface, however with the rapid loading expected today, be wary of fresh slabs and drifts. Watching for current wind loading and cracks shooting from your skis/board will be good ways to suss out if slabs are sensitive.


Additional Concern

It is time to put glide avalanches back on our radar. With warming temperatures we could see a number of glides cracks open up and release in the next several days. Yesterday, we saw a slab that has moved during the past week and looks ready to avalanche. Staying out from under glide cracks will be key this week.

Glide slab in the Seattle Creek drainage (East facing ~2,000'). 


Mountain Weather

Weather yesterday was relatively mild with overcast skies, light winds from the East and Northeast and only a trace to an inch of snow accumulating above 1,000' (rain below). 

Overnight, temperatures and winds have increased at all elevations as the leading edge of a large and complex low pressure system moves in from the Gulf. We can expect up to an inch of rain to fall throughout the day below 1,500' with 6-10" of wet snow above. Winds have already begun to climb and will be blowing from the East in the 35-45mph range. Temperatures are also climbing and should top out around 30 deg. F on the ridgetops and the upper 30'sF at 1,000' on Turnagain Pass.

For Monday, precipitation intensity will diminish slightly with forecast amounts around .5" of rain and 3-5" of snow (rain/snow line ~1,200'). Winds will continue from the East and should diminish slightly as well. Temperatures will remain warm, near 30F on the ridgetops and the upper 30's at 1,000'. It looks as though it will be Wednesday before temperatures cool back off for snow to make it down near sea level.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 34  0.1  20 
Summit Lake (1400') 33   5
Alyeska Mid (1700') 33  0.22  17 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 29  16  55 
Seattle Ridge(2400') 29  NE  18 46 

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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