Avalanche Advisory

Turnagain Area Avalanche Advisory
Tuesday, March 6th 2018 4:45 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 remains MODERATE above 1000’ on all aspects. Triggering a large slab avalanche breaking in weak layers 1-3' deep in the snowpack remains possible. Watch for old wind slabs along ridgelines and in cross-loaded gullies. Evaluate snow and terrain carefully. 

 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.
Special Announcement

Human triggered avalanches continue to be reported region-wide, one at Hatcher Pass and another in the Western Chugach (Hiland Road) occurred Sunday. Snow last week followed by strong winds increased the avalanche conditions, which may continue to linger in many areas of Southcentral, Alaska.


Avalanche Problem 1

Persistent Slabs

Almost Certain
Very Likely


Very Large


Observers continue to find the buried persistent weak layers in the snowpack to be reactive and the possibility of triggering a large avalanche remains.  One observer yesterday found the January 21st buried surface hoar, described the snowpack they found in Lynx Creek as "spooky" and changed their plan due to concerning snowpit test results. This buried surface hoar layer was also observed to be reactive on Magnum yesterday as well. As snow starts today and hopefully falls throughout the week it will be important to remember the current state of the snowpack. Buried 1-2' deep are facets sitting on a crust at the mid-elevations and 1-3' deep is a buried surface hoar/facet combo at the higher elevations. The slab over the weak layers could be very hard if it is in terrain that was affected by the strong winds last week. This was the case in the skier triggered avalanche in Summit Lake a week ago, the mid-elevation faceted layer was under very hard wind-affected snow.  Although the heart of Turnagain Pass has the buried weak layers, they are more pronounced and developed on the Southern end of Turnagain Pass and in Summit Lake where the snowpack is shallower. Areas to the North, such as Crow Pass, are also suspect along with those that have not seen much traffic this season. Using safe travel protocols and assessing the consequences if a slab does release is key in choosing terrain. Weak layers like these can become more reactive after even a small additional load. As the snow falls this week keep that in mind and as always be alert for signs of instability. 

Wind slabs: Hard wind-affected snow on steep, unsupported slopes may still triggered if you find the wrong spot. Be suspect of very stiff snow over soft snow or hollow sounding snow near upper elevation ridgelines and cross-loaded gullies. If winds really pick up this afternoon pay attention to changing conditions. 

Snowpit on Magnum yesterday at 3100'. The January 21st buried surface hoar is easy to spot and still reactive in stability tests. 


Cross-loaded gullies on Seattle Ridge


Mountain Weather

Yesterday was mostly to partly cloudy with some afternoon sunshine peeking through. Temperatures were in the teens to mid 20Fs. Winds were light and variable. Overnight temperatures were in the teens to low 20Fs and winds remained light. 

Today will be mostly cloudy with afternoon snow showers. Temperatures will be in the teens to high 20Fs and winds will start off light and increase from the Southeast 10-20 mph gusting into the 30s. Tonight there is snow in the forecast with 2-6" possible. Temperatures will be a bit cooler in the low 20Fs to mid teens. Winds will continue from the Southeast. 

Tomorrow's forecast has continued snow showers in the morning, clearing in the afternoon and then more snow in the forecast overnight. The next low pressure is lining up for more snow on Thursday but details are uncertain. However, the week ahead looks to be snowy.  From the NWS discussion this morning: Despite March and April being the driest months of the year (climatologically), Mother Nature is giving that statistic a run for its money. Fingers crossed!  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 22   0  68
Summit Lake (1400')  12    0  0    29
Alyeska Mid (1700')  19    0  0      59 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 15  6  14
Seattle Ridge(2400')  20 varible   3  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: Mar 15, 2018 )

Glacier District
Johnson Pass: Open
Placer River: OpenPlease avoid private property and AKRR job site at Luebner Lake. Cross railroad tracks if needed, do not ride down tracks, it is illegal.
Skookum Drainage: OpenCross railroad tracks if needed, do not ride down tracks, it is illegal. FYI, Skookum drainage closes to Snowmachines on 4/1 as per the Chugach NF plan.
Turnagain Pass: Open
Twentymile: OpenCross railroad tracks at designated spot as you leave the parking area.
Seward District
Carter Lake: Open
Lost Lake Trail: Open
Primrose Trail: Open
Resurrection Pass Trail: OpenResurrection Pass trail is open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Open
South Fork Snow River Corridor: Open
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.

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