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Avalanche Advisory

Turnagain Area Avalanche Advisory
Saturday, January 12th 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

Strong winds impacting the region today will cause the avalanche danger to rise to MODERATE at all elevation bands in exposed terrain as triggering a wind slab becomes possible. As these slabs build over the weak surface snow the danger may rise to CONSIDERABLE in the Alpine later in the day. Natural avalanches may become possible and human triggered avalanches may become likely. Pay attention to changing conditions. In addition, glide cracks may release into avalanches. Limiting/avoiding exposure under them is prudent and give cornices a wide berth. 

There is a Winter Weather Advisory issued for 9 pm this evening to 11 am Sunday for Portage Valley and Turnagain Pass. 

SUMMIT LAKE / JOHNSON PASS / LYNX DRAINAGE: Keep in mind buried weak layers exist in the middle and base of the snowpack. More potential for triggering a large slab avalanche exists in this zone, especially with wind-loading. Choose terrain wisely.

 

 

 

 

 


 Show the Complete North American Avalanche Danger Scale
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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.
Special Announcement

The 11th Annual Alyeska Ski Patrol Auction benefiting the Alyeska Ski Patrol Avalanche Canine Program is tonight from 8-10 pm at the Sitzmark! Enjoy the "entertainment" and bid on an early morning ski with your favorite patroller.

For the Saturday morning Hatcher Pass avalanche forecast click HERE




Avalanche Problem 1

Wind Slabs

Almost Certain
Very Likely
Likely
Possible
Unlikely

Chance

Historic
Very Large
Large
Small

Size

After enjoying sunny skies and a mostly stable snowpack a series of storms will begin to affect the advisory area today. Temperatures are on the rise, winds are increasing and precipitation will start to fall later in the day. Today is the day to expect changing conditions and be on the lookout for signs of instability. Initially increasing winds may trigger small loose snow avalanches but as they continue and intensify, wind slabs will build in exposed terrain. There is soft snow available for transport and wind slabs may be quite tender as they develop over very weak surface snow formed during the cold weather. Well developed surface hoar was observed at lower elevations and along some ridge tops. Near-surface faceted snow was observed at all elevations. Below 1500' there is a crust below the weak snow. This is not a good set-up for new snow and wind-loading. Look for blowing snow, cracking, collapsing and be especially heads-up if natural wind slabs start releasing. 

Rapidly warming temperatures and the additional blowing snow may also make cornices easy to trigger over the next few days. As always, give these a wide berth. 

 

 Weak surface and just below the surface snow on Center Ridge, 1-10-19. 

 Weak surface snow on the Gold Pan ridge, 1-11-19. Photo: Allen Dahl


Avalanche Problem 2

Persistent Slabs

South of Turnagain - Lynx Creek/Johnson Pass/Summit Lake zone:  As the weather pattern changes and the potential for wind loading increases it becomes even more critical to remember that a poor snowpack structure exists in these areas. The Christmas buried surface hoar has been found as well as concerning facet/crust combinations in the bottom of the snowpack. Avalanches may initiate near the ground and be quite dangerous. If you're headed this way, evaluate terrain exposure and the snowpack as you travel. Be on the lookout for signs of instability. 


Additional Concern

Glide Avalanches

Identify glide cracks and avoid spending any time under these features. Glide cracks are opening and have avalanched within the last week. Glides are completely unpredictable and not human triggered. The rapid temperature rise and additional snow load over the next few days may or may not cause an increase in glide activity. 


Mountain Weather

Yesterday: Skies were clear and temperatures were cold with daytime highs in the single digits. Valley bottoms remained below zero. Winds were light and easterly. Overnight clouds bulit and temperatures began to increase.

Today: Mostly cloudy skies with an increasing chance of precipitation throughout the day. Temperatures will continue to rise into the 20Fs. Easterly winds will build and blow 15-25 mph with gusts into the 40s. These are forecast to increase overnight. Snowfall will increase overnight and temperatures will rise with the potential for rain to fall at sea level. 

Tomorrow: Cloudy skies and snow continues tomorrow with the brunt of the storm in the early morning. Winds will remain strong and temperatures will continue to rise with the warmest temperatures on tap for Monday. The series of fronts and lows are forecast to impact the region into the week. 

*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  0  53
Summit Lake (1400') -1    0   20  
Alyeska Mid (1700')  0  41 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  6 SE   6 23 
Seattle Ridge(2400')  8 *N/A  *N/A  *N/A 

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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