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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Saturday, March 25th 2017
Created: Mar 25th 4:08 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.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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The Bottom Line

The avalanche danger is MODERATE on all aspects and elevations today. Triggering a slab avalanche 1-2' thick or loose snow avalanche is possible on slopes 35 degrees and steeper. Sunny skies and warming afternoon temperatures could make Southerly slopes more avalanche prone later in the day. Watch for changing conditions. Avoid travel on or under cornices and give glide cracks a wide berth.

Sunny Saturday with soft snow = Good travel habits are important! Expose only one person at a time on a slope, watch your partners closely, have an escape route planned in case the snow moves and pay attention to other parties in the same terrain. 

Summit Lake: Read the Saturday Summit Lake Summary HERE.  


Primary Concern

Yesterday was the first day since last weekend's storm that avalanches were not reported. It has been five days since the storm ended and the weak surface snow (near surface facets and surface hoar) from the March high pressure/drought was buried. Slab depths vary across the advisory zone due to the range of storm totals from 6" to 2+ feet. Most of the avalanches that have occured have been small human triggered pockets and not well connected; a testament to the relatively cold weather this week keeping the new snow loose and mostly unconsolidated. The slabs that have released have been in places where the slab is more cohesive, either due to wind effect or warmth/settlement. On Thursday one of the avalanches that was observed was thought to have been a natural that occured later in the day from warming and direct sunshine. 

For today, with similar weather to the past few days, we can expect similar avalanche conditions. Triggering a slab avalanche is still possible. Things to keep in mind are:

  1. Southerly facing slopes receiving direct sunshine are suspect later in the day (these zones also have an old sun crust acting as a bed surface).
  2. Obviously wind loaded/pillowed slopes. If you find an old wind slab, it is likely sitting on weak faceted snow and may be triggered on steeper slopes.
  3. Remember, below last weekend's new snow sits old weak faceted snow - quick hand pits can help assess bonding with this old layer that is 1-2' below the surface.

Snow pit on Tincan Common. APU Snow Science Class

 


Additional Concern

LOOSE SNOW AVALANCHES (SLUFFS):  Human triggered dry loose snow avalanches continue to be easily triggered on steep slopes without a sun or wind crust on the surface. Watch your sluff if headed to these steep lines with loose surface snow, they could be larger and run further than expected. Pay attention to Southerly slopes as the afternoon temperatures become warmer. We could start seeing more wet loose avalanches from direct sunshine; cold temperatures have keep these to a minimum lately. Look for roller balls as an indication of surface snow warming. 

CORNICES:  There has been a couple of cornice breaks after the storm and cornices are always worth giving a wide berth. Direct sunshine and warming can help to loosen them. 

GLIDE CRACKS:  Glide cracks continue to slowly ooze open on Seattle Ridge, Tincan's Library, Lynx creek and other zones. Keep an eye out for them and limit time spent underneath.

Sluffing on Magnum observed on Wednesday. 


Mountain Weather

Yesterday was sunny and clear with temperatures in the 20Fs in the valleys and teens at ridgetops. Winds were light and variable. Temperatures dipped into the single digits overnight and skies were mostly clear.

Today the sunshine will continue with a similar temperature pattern and winds will remain light. Clouds are forecasted to roll in this evening and there is a chance of snow overnight. 

Tomorrow will be mostly cloudy with a chance of snow showers and slightly warmer temperatures. According to the National Weather Service "Real change continues to be advertised by all models early into next week and the bottom line is that the pattern is now on the verge of change and the days of cold and endless sun are going on a brief hiatus." The track of the low moving into the Gulf is still uncertain. Stay tuned!

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 15   0 63 
Summit Lake (1400') 13  0 29 
Alyeska Mid (1700')  20  0 58

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 11  10 
Seattle Ridge(2400')  12 variable   11

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: Dec 08, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedRain and snow have fallen in Turnagain Pass this week, but not enough to open for snowmachining. Continue to check back to this site for updates.
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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