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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Tuesday, March 7th 2017
Created: Mar 7th 5:17 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
Special Announcement

Avalanche Rescue Talk:  Stop by Ski AK in Anchorage for a discussion on backcountry rescue TONIGHT! The focus will be on organized rescue, presented by Bill Romberg (AMRG) a rescue specialist with 150 Search and Rescue missions here in Alaska. The evening will begin with a short 'state of the snowpack' report by the CNFAIC. See you TONIGHT - more details HERE!!


The Bottom Line

The avalanche danger is LOW at all elevations.  Avalanches are unlikely today.  Exceptions to this are possible, mainly in the form of old wind slabs, loose snow avalanches and cornice falls.  Big alpine terrain and steep slopes in the lower elevations will be the most likely places to encounter these issues. Remember to give glide cracks a wide berth and limit exposure under them. 

Good travel habits remain important.  These include exposing only one person at a time on a slope, watching your partners closely and having an escape route planned in case the snow moves. 

Summit Lake area:  A thinner snowpack exists with a poor structure and heightened avalanche danger remains in this zone. Please see the Saturday Summit Summary HERE


Primary Concern

With a bit of a "Groundhog Day" feel our weather remains cold and clear and our snowpack is in a holding pattern of sorts. It has been 14 days since the last measureable precipitation and a week since the beginning of the Northwest 'wind event'. Several large wind slab avalanches have occurred over the past week, most of these in the Summit Lake area South of the forecast zone. However, we did get a report of a suspected natural wind slab avalanche in the Girdwood Valley Sunday, on the North end of the forecast zone. This was on an upper elevation, Southwest facing slope, under Goat Mountain. 

If you are headed to the mountains, the avalanche conditions are in a 'Normal Caution' regime.  LOW avalanche danger doesn't mean no avalanche danger. This means avalanches are unlikely, but not impossible. Things to watch for and keep in mind will be:

Wind Slabs:
Old, stubborn and hard wind slabs could pop out in steep and rocky terrain. This is most likely where weak faceted snow sits under shallower hard slabs - usually found in the steep rocky thin zones. Watch for hard snow over weak loose snow as well as shooting cracks and whumphing noises. If winds ramp up today look for active loading along ridgelines however, there isn't much snow left to move...

Loose Snow (Sluffs):
Dry sluffs on steep slopes are getting larger in areas harboring loose surface snow - watch your sluff! Also, with direct sun and depending on what the winds do today the Southerly aspects could become damp or wet in the afternoon. This may cause natural wet/damp loose snow avalanches on some steep Southerly slopes and/or make it more likely to trigger one.

Glide Avalanches:
Glide cracks continue to slowly open in the advisory area. These could release at any time, watch for the cracks in the terrain and avoid being under them.

Cornices:
There was a natural cornice fall in the Kern drainage observed on Friday (exact release time frame unknown). Cornices should always be given a wide berth from above and limit exposure time traveling underneath.

Persistent Slabs and Deep Slabs: 
There are various weak layers in our thin snowpack; the snowpack is roughly half of what it normally is this time of year. Buried surface hoar sits 1-3+' below the surface and faceted snow sits in the mid and base of the pack. These various weak layers with varying degrees of strength are in a dormant stage due to a lack of weather and ample time to adjust. Although this means the layers are not producing avalanches, it doesn't mean an outlier can't occur which causes a large avalanche breaking deeper in the pack. 

Cornice in Petersen Creek yesterday. This is a good example of a cornice that could break farther back than expected. 


Mountain Weather

Yesterday was clear and cold with temperatures mostly in the single digits. Winds were calm. Overnight temperatures dropped below zero. 

Today will be very similar with the exception of a chance for stronger winds in the afternoon. Overall we are experiencing "a dry and stable pattern locked in place for the foreseeable future" --National Weather Service Discussion. There is a warming trend forecasted for the end of the week as warm air aloft pushes into the region. 

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  3  61
Summit Lake (1400')  0 0  29
Alyeska Mid (1700')  5 0  57

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  3  W 12 
Seattle Ridge(2400')  3  NE  15

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: Nov 18, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedOnly a few inches of snow sits at the motorized lot, not enough to open for snowmachining at this time. Updated Nov. 18, 2017
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to 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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