Avalanche Advisory

Turnagain Area Avalanche Advisory
Friday, March 9th 2018 4:43 am by Heather Thamm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger is HIGH at all elevations where natural and human triggered avalanche 2-4+ feet deep are likely today. An avalanche from above could run farther and faster than expected and has the potential to reach valley bottoms. Travel in avalanche terrain is not recommended including being under the runout of larger slopes above. This will be extra important for the popular areas of Placer Valley, Turnagain Pass and Portage Lake. 

 Show the Complete North American Avalanche Danger Scale
4 High Alpine / Above 2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Treeline / 1,000'-2,500' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
4 High Below Treeline / Below 1,000' Travel Advice: Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
Special Announcement

**Dangerous avalanche conditions are region wide across the Kenai Peninsula due to heavy snowfall and strong winds. This includes Seward to Summit Lake. Expect avalanche danger to remain elevated through the weekend. A winter storm warning issued by the National Weather Service will remain in effect through 5pm today for the Eastern Kenai Mountains and the Seward Highway. 

Avalanche Problem 1

Storm Slabs

Almost Certain
Very Likely


Very Large


Two feet of new snow and strong winds (up to 96mph) over the last 24 hours have created dangerous avalanche conditions for our entire region (Girdwood, Turnagain Pass, Portage, Placer Valley and Summit Lake.) Strong Easterly winds 20-40mph will continue through late afternoon and 5-10” of additional snow is expected today. Natural avalanches 2-4+ feet deep are likely and human triggered avalanches are very likely. Precipitation has remained snow to sea level, and cold snow means avalanches could run faster and farther than expected. Avoiding avalanche terrain is necessary today, which includes staying far away from runout zones of larger slopes above. Later today as winds decrease and snow stops falling be careful not to get tempted into steeper terrain. This new snow has fallen on hard surfaces and weak snow below and bonding will be poor. An avalanche from above could run into valley bottoms, especially in places like Seattle Ridge, Portage Lake and Placer Valley.   

Storm totals as of 6am:

  • Turnagain Pass: 20-26 inches (1.0” SWE)
  • Girdwood: 18-22 inches (1.3” SWE)
  • Portage: 20-24 inches (1.1” SWE)
  • Summit Lake: 10-14 inches ( 0.5” SWE)

Types of storm snow avalanches that are expected today:

-  Wind slabs:  Slabs up to 2-4 feet thick due to strong winds loading leeward aspects and terrain features
-  Storm slabs:  Soft slabs (2 feet deep) are expected in areas out of the wind due to rapid loading and poor bonding with the old surface
-  Cornice falls:  Cornice fall could trigger a wind slab or storm slab below

AKDOT snowstake at Turnagain Pass is showing around 2 feet of new snow in the last 24 hours. 

Yesterday at the beginning of the storm observers experienced strong winds even in the mid elevations. Photo taken at 12pm (3/8/18) at Sunburst around 1800'. 

Avalanche Problem 2

Persistent Slabs

Almost Certain
Very Likely


Very Large


A storm related avalanche could ’step down' into a deeper weak layer causing a very large avalanche to send debris well into valley bottoms. Another reason to let the mountains sit as the storm moves out of our area. Areas on the South end of Turnagain Pass and the Summit Lake area are most suspect for having deeper weak layers release.

Several widespread persistent weak layers exist within our snowpack region wide including buried surface hoar and facets 1-2' below the old surface. Don't forget we haven't had a storm like this in months. Lots of uncertainty exists around how our old weak snowpack will adjust to its new load. 



Mountain Weather

Over the last 24 hours 18-26 inches of snow has fallen across our forecast zone. Yesterday Easterly winds increased into the 60’s mph in the afternoon with gusts into the 90’s mph. Overnight Easterly winds decreased into 20-40mph range. Temperatures at 3000’ have been in the low 20F’s and temperatures at sea level have been around 33F.

Today another 5-10 inches of snow (.5” SWE) is expected through mid afternoon and scattered snow showers this evening. Southeast winds will continue to be strong (20-45mph) and decrease to 15-25mph by late-afternoon. Temperatures at 3000’ will be in the mid 20F’s and temperatures at sea level may increase into the mid 30F’s, but precipitation is expected to remain as snow at sea level.  

Snow showers are in the forecast through the weekend, but precipitation amounts remain uncertain. For Saturday winds are expected to be light from the East and temperatures in the upper elevations will be in the low to mid 20F’s and temps at sea level will be in the upper 20F’s to low 30F’s. 

*Temperatures at Center Ridge weather station have been reporting warmer temps compared with other weather stations at this same elevation band. There have been some issues with this temperatures sensor this winter. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') *31  26  1.0  93 
Summit Lake (1400') 28  14  0.5  44 
Alyeska Mid (1700') 27  18  1.36  77 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 18  ENE  37  96 
Seattle Ridge(2400') 23  26  62 

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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