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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, March 8th 2015
Created: Mar 8th 6:03 am
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'
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The Bottom Line

There is a MODERATE avalanche danger today in the Turnagain Pass region where 8-10" of new snow and wind has formed sensitive wind slabs. These slabs are expected to be 8-14" thick and easy to trigger on slopes over 35 degrees. In areas where the wind has not affected the snow, sluffs should be expected and large enough to be a legitimate concern in steep and sustained terrain.

Keeping a close eye on the new snow and watching for, and avoiding, any wind loaded slopes will be the key for a fun powder day.

***If you are headed to Hatcher Pass today, there is a HIGH avalanche danger. Please see the Hatcher Pass Avalanche Center website for more details.


Primary Concern

Could we really see a hint of winter now that we are well into March? Now that we just switched over to Daylight Savings Time? Why not... It seems like all bets are off these days and we will take what we can get! Below are mid-elevation storm totals from a cold front that moved over Alaska Friday night through yesterday:

Turnagain Pass - 10"
Girdwood Valley - 8+"
Summit Lake - 3-6"
Hatcher Pass - 12-18"

WIND SLAB:
On the heels of this much anticipated new snow has been a cold Northwesterly wind. The winds produced plumes off some, but not all, peaks in the region yesterday afternoon and have continued to blow in the 15-20mph range overnight. This is prime speed for wind slab development and human triggered wind slab avalanches should be expected. Additionally, this flow direction is ideal for loading the East face of Seattle Ridge.

Yesterday, we were able to find and trigger a small wind slab just before the winds kicked up. Today, these types of avalanches should be a dime a dozen and easy to trigger. Slab depths are on the shallow side, 8-14", yet could be stiff enough to support the weight of a person; this is concerning as the slab may allow someone on to it before breaking above them. The good news is, wind slabs should be easy to identify with their smooth rounded surface and upside down feel (harder snow over softer snow). Quick hand pits are a great way to see how the new snow is acting and I'd recommend a number of these as you move through the mountains. 

Photo below is of an easily skier triggered soft wind slab yesterday on Sunburst's Southwest face (3,000' average depth 10"). 

 

Winds transporting snow on Mount Alpenglow yesterday afternoon.


Secondary Concern

Watch your sluff. Sluffing in Friday/Saturday's storm snow was prevalent yesterday and will be again today. These sluffs are entraining a significant amount of snow on sustained steep slopes and in channeled terrain. The cold temperatures will help to keep sluffs on the radar.


Mountain Weather

It is very nice to finally have some new snow to report. Besides the storm totals above, see the chart below for the past 24-hour totals. The rain/snow line with this event hovered between 500 and 1,000' and 3" of wet snow (which has now frozen) fell at the parking lots at Turnagain. Snowfall shut down around noon yesterday and was followed by a switch in wind direction from the South to the Northwest. Cold air has and is currently being ushered in by the Northwesterly flow.

Today, visibility should be good with mostly sunny skies and a few lingering clouds. However, the cold Northwest winds are expected to remain in the 15-20mph range with higher gusts. Temperatures will continue to drop through the day into the teens at most locations, then to the single digits by tonight.

As we head into the early part of this week, no precipitation is expected as we will remain in a cold and blustery Northwest flow. 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  28 0.3  45 
Summit Lake (1400')  29 0.3 
Alyeska Mid (1700')   30   0.27   29 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 20  12  43 
Seattle Ridge(2400') 23  n/a  13  42 

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 16, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedThanks all for a safe and fun season on the Chugach NF! Stay tuned for the 2017/18 season. #playsafe #snowtosealevel
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail will be open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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