Avalanche Advisory

Turnagain Area Avalanche Advisory
Thursday, March 26th 2015 7:00 am by Graham Predeger
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

The avalanche danger in the backcountry will climb to MODERATE as a spring storm enters the advisory area with a change in weather from the past few days.  Above treeline 8-10” of new snow coupled with 20-40 mph winds from the East will build wind slabs in the 1-2 foot range.  These will be sensitive to human triggers today, particularly on north and west (leeward) slopes. 

Near treeline, a rain/ snow mix may be enough to initiate wet loose activity or potentially a wet slab avalanche in steep terrain.

An additional concern to be aware of during this first week of spring comes in the form of growing and weakening cornices.  Simply put; avoid them.

 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.
0 NO RATING Below Treeline / Below 1,000'
Special Announcement

CNFAIC staff have completed an accident report for the avalanche fatality in Cantwell on March 14th, 2015.  This is Alaska's second fatal avalanche of the 2014/15 season and the seventh in the US this winter.  Please take a few minutes to read this report and share it with your skiing and riding partners as there is always a lesson to be learned in light of a tragic accident such as this.

Avalanche Problem 1

With another spring storm moving in from the southeast we can expect wind slabs to be touchy for the next 24 hours, particularly above 2,000’ as moderate easterly winds rake through the advisory area.  This is a direct-action avalanche problem meaning we can expect fresh wind slabs to be sensitive to human triggers during and immediately following this storm.   Expect wind slabs to be in the 12- 24” range and relegated to the new snow accumulating on slick sun crusts  and weak faceted snow.

Red flags such as shooting cracks or whumphing in the snowpack are likely to be present in areas where wind slabs exist and should be interpreted as nothing other than unstable snow!  Best practices today and during this storm will be to avoid convexities and steep rollovers where these fresh wind slabs exist.  This is particularly important if a slope ends in a terrain trap such as a gully or flat bench where avalanche debris can accumulate.

Avalanche Problem 2

Temperatures yesterday were very warm for March.  If the rain/ snow line climbs to near 2,000’ today, wet loose avalanches may come in to play.  Wet loose activity or roller balls may initiate a wet slab near treeline elevations as well.  Given the freeze/ thaw activity over the last week, the potential for a wet slab release is low but worth mentioning if temperatures rise and rain on snow becomes a reality.

Seattle ridge as seen from the motorized parking lot looking North.  This photo was taken at 5:30pm and the temperature at 1,000' was 46 degrees.  

Additional Concern

Cornices will further ripen with today’s sticky spring-storm.  We haven’t seen these fail naturally in earnest yet but rest assured they are losing strength and drawing closer to that point of failure.  Though beautiful to look at, avoid time spent below a cornice and stay well back from corniced ridges.

Mountain Weather

Yesterday saw the slow approach of a front associated with a low in the northeast Gulf of Alaska.  Skies were partly cloudy and winds moderate to strong at times from the east.  The real outlier was how warm ambient air temperatures were with Center ridge (1880’) topping out at 47 degrees yesterday and low 50’s seen around Portage.

The storm showed up in earnest around 11pm last night with wet snow falling at Turnagain pass (1000’) and snow accumulations in the 2-5” range this morning.  Today expect a stormy day with the rain/ snow line to be around 1000’.   Up to another .4” of water (4-5” of snow) is expected today with ridgetop temperatures in the high 20's.  Winds will be out of the east 20- 40mph then shifting southeast this evening.

Unsettled weather looks to be in our future through the weekend as another North Pacific low tracks south of Kodiak by Saturday.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 37   2 .2  57 
Summit Lake (1400')  38 12 
Alyeska Mid (1700') 38   2 .33  31 


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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  27  E 28   70
Seattle Ridge(2400') 30   n/a 16   71

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: Oct 05, 2019 )

Glacier District
Johnson Pass: ClosedClosed
Placer River: ClosedClosed
Skookum Drainage: ClosedClosed
Turnagain Pass: ClosedClosed
Twentymile: ClosedClosed
Seward District
Carter Lake: ClosedClosed
Lost Lake Trail: ClosedClosed
Primrose Trail: ClosedClosed
Resurrection Pass Trail: ClosedClosed. Will be open for the 2019/20 season pending adequate snow cover.
Snug Harbor: ClosedClosed
South Fork Snow River Corridor: ClosedClosed
Summit Lake: ClosedClosed

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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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