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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, February 26th 2019 7:00 am by Aleph Johnston-Bloom
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is MODERATE on slopes over 35 degrees above 2,000'. Triggering a slab resting on weak faceted snow is still possible. Slabs could be anywhere from 6" to 2' thick depending on prior wind-loading. Additionally, pay attention to changing conditions with warm temperatures in the Alpine, especially on steep slopes in direct sunshine. As always, give cornices a wide berth, limit exposure under glide cracks and watch your sluff. 

SUMMIT LAKE / JOHNSON PASS:  Triggering a larger, more dangerous slab remains a concern due to variety of old weak layers in the mid and base of the snowpack. Extra caution is advised. Evaluate snow and terrain carefully. 

SEWARD / LOST LAKE:  Slabs up to 2' in depth could be found and triggered in this area on steep wind-loaded slopes.

 

 


 Show the Complete North American Avalanche Danger Scale
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
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.
Special Announcement

Take a minute out of your day to help the Community Snow Observations crew with gathering snow depth information in Alaska!! Website is communitysnowobs.org. It's easy to do, you just need a smart phone, 30 seconds and your probe to measure the snow depth.

 


Avalanche Problem 1

Persistent Slabs

Almost Certain
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Chance

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Yesterday Alpine weather stations recorded above freezing temperatures for most of the day.  The weather station on Max's Mountain (3200') above Girdwood recorded a high of 42F at 5 pm. Some small wet loose avalanche activity was observed as well as some "sticky" surface conditions on slopes getting direct sunshine. No new slab avalanche activity was reported. After a night with temperatures dipping below freezing and clear skies expect crust in the morning on surfaces influenced by yesterday's warming. Watch for changing conditions again during the heat of the day. The Valentine's near surface facets sitting around a foot below the surface is the main persistent weak layer of concern. As the days pass since our last loading event the likelihood of triggering an avalanche has decreased. However warming can sometimes make slabs resting on persistent weak layers more easy to trigger and stability tests are still showing that this layer has the potential to avalanche. 

What to keep in mind today:
    -  Wind-loaded, steep, unsupported slopes are the most suspect for popping out a slab that may be sitting on weak snow.
    -  Larger and more dangerous avalanches are possible in the Summit Lake and Johnson/Bench peak area where a thinner snowpack exists with multiple weak layers. 
    -  SUN EFFECT and moist/wet sluffs on or under steep rocky southerly terrain. On wind protected, shaded, steep slopes watch for facet sluffing.
    -  Cornices. Warmer temperatures at higher elevations can help loosen these monsters and with good weather and ridgeline travel, don't forget to give cornices a wide berth.
 And remember to practice safe travel protocol

 

Slab over the Valentine's facets, 2.22.19. This set-up has been noted across the advisory area.

 

Wet loose avalanches on Goat, 2.25.19


Additional Concern

Glide Avalanches

Glide cracks are unpredictable, not associated with human triggers, and can release without warning at any time.  The best way to manage this problem is to avoid traveling on slopes directly below glide cracks. A short list of known cracks in popular zones:  Magnum, Lipps, Seattle Ridge, Eddies, Lynx Ck. See a new glide crack or one that appears to be opening up? Please snap a photo and send us a quick ob!

Glide cracks on Magnum, 2.25.19. Photo: Nikki Champion


Mountain Weather

Yesterday: Clear and sunny! Temperatures were in the 30Fs to low 40Fs in the Alpine and in the teens to mid 20Fs at lower elevations. Winds were very light and easterly. Overnight temperatures in the Alpine were in the low 30Fs to high 20Fs. Valley bottoms were in the single digits to low teens, skies were clear and winds were calm.

Today: Another day of sunshine and a temperature inversion. Expect 30Fs-40Fs at upper elevations and teens to 20Fs at lower elevations. Winds remain light. Temperatures will drop again overnight with clear skies and the inversion will continue. 

Tomorrow: The ridge of high pressure is still very much in place and the current weather pattern is expected to continue into the weekend. We may see a few more clouds later in the week but overall more of the same. Seems like a good time for a snow dance! Marvelous March powder???

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  25   0   60 
Summit Lake (1400')  13    0    29 
Alyeska Mid (1700')  23 55 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 31   SE  3 11 
Seattle Ridge(2400')  30    E  1   6  

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: Mar 22, 2019 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Open
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: Open
Twentymile: ClosedClosed as of 3.20.19 due to lack of snow.
Seward District
Carter Lake: Open
Lost Lake Trail: ClosedClosed as of 3/22. Unfortunately HEAVY rain over the past week has washed much of the snow off the lower stretches of this trail.
Primrose Trail: OpenPlease stay on trail to avoid resource damage through forested areas.
Resurrection Pass Trail: ClosedClosed for the 2018/19 season. Next season will be open to motorized use.
Snug Harbor: Open
South Fork Snow River Corridor: ClosedClosed as of 3.20.19 due to lack of snow.
Summit Lake: Open

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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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