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Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, January 30th 2018 4:36 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 above 1,000' for triggering a slab avalanche 1-3' thick. Slopes with signs of recent wind loading will be the most suspect for triggering an avalanche. Additionally, watch for easily initiated loose snow avalanches (sluffs) on steep 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.
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.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

The 1-2' of snow that fell on January 26th, loaded a layer of widespread surface hoar that was buried on January 21st.  Snow falling on a persistent weak layer is generally a cause for concern. However, the snow was so light the avalanche activity over the weekend only occurred on slopes where the snow was just cohesive enough from wind effect to act like a slab. The advisory area received additional wind Sunday night, that moved snow around and affected surface conditions, especially in Girdwood Valley where the winds were stronger and more sustained. There were no reported human triggered avalanches yesterday. Despite the cold and clear weather now slowly faceting away the slabs, there is still the possibility of finding and triggering lingering slabs in leeward terrain today.  Remember that the surface hoar is lurking underneath the recent snow. Pay attention to areas where the snow feels stiff, looks pillowed or sounds hollow and watch for shooting cracks. 

Snow pit from Lynx Creek that shows the surface hoar under the new snow. In this pit it was not reactive. 

Small avalanche in God's Country. The snow along the ridge is noticably wind affected. This avalanche may have been remotely triggered (tracks not in photo) over the weekend or a natural from winds on Sunday night. 

 


Avalanche Problem 2

Dry Loose

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

Watch your sluff - loose snow avalanches ‘sluffing’ is possible on steep terrain features protected from wind. As the cold weather continues to loosen and facet the surface snow, expect sluffs to become larger and faster by the day.

Evidence of natural dry loose avalanches on Lipps. 

 


Additional Concern

Deep Persistent Slabs

Triggering a deep slab is becoming unlikely, but is still not out of the question above 3000'. In the high elevation snowpack there are a variety of weak layers in the mid pack and near the ground. Because of this poor structure, there is still a chance of triggering a deep slab if you find the wrong spot. The most likely trigger spots are in thin areas in the snow cover, often near rocks, or where the slope rolls over. 


Mountain Weather

Yesterday was clear and sunny. Temperatures were in the single digits to mid teens and the inversion remained in place. Winds were variable depending on location and stronger near Girdwood dying off in the afternoon. Overnight temperatures were in the single digits and low teens and dropped below 0F in many valley locations. 

Today will be clear and sunny again with temperatures in the single digits to high teens. Winds will be calm. Tonight clouds are forecast to increase.

Tomorrow will be cloudy as a low moves into the Western Gulf bringing snow to Kodiak and sending clouds our way. Sunny and clear weather looks to be the theme again for the remainder of the week into the weekend. There is discussion of pattern change bringing warmer air and precipitation but the timing 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 67 
Summit Lake (1400')  0  0 0 18 
Alyeska Mid (1700')  11  0  0 53 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 10  NE   20
Seattle Ridge(2400')  12 variable   3 10 

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 06, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

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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