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Avalanche Advisory

Turnagain Area Avalanche Advisory
Monday, March 25th 2013 5:52 am by John Fitzgerald
Updated: Mar 25th 14:52 pm
ARCHIVED ADVISORY - All advisories expire after 24 hours from the posting date/time.
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The Bottom Line

*******************************UPDATE 2PM********************************************************

Precipitation intensity and storm totals have exceeded forecasted amounts from this morning.  Natural avalanche activity has been reported in the Girdwood Valley and south of Summit Lake.  The avalanche hazard is elevated as a result to CONSIDERABLE above treeline and MODERATE below treeline.  Natural avalanches are possible and human triggered avalanches are likely in areas that have received new snowfall amounts greater than 12".  See below for specific avalanche concerns and areas to avoid.

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 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

Next Sunday is the 2nd ANNUAL CORN HARVEST - get it on your calendar now !! Come join the CNFAIC Friends and Forecasting staff on Turnagain Pass for free food, games, prizes, etc. This is one way we would like to thank all of you for your dedication and support. Oh, did I mention, it’s FREE?

 


Avalanche Problem 1

In areas unaffected by wind expect to encounter enough light density snow for riders and skiers to create small to medium sized loose snow avalanches.  The only reactive snow we were able to find yesterday was a few inches of this light density loose snow.  In terrain over 40 degrees this surface snow slid readily in the form of sluffs and was low in volume and fast moving.  Expect more of the same behavior today with volumes increasing as the snow accumulates.  Human triggered sluffing has the potential to carry people into and over terrain traps.  Choose your terrain with this in mind today.

Storm Snow

New snow in the form of slabs will also be a concern.  Expect slabs up to 18" in depth to be most sensitive on steep south facing terrain today.


Avalanche Problem 2

Look for wind slabs to build today in the upper elevations on west and south aspects.  These slabs will be most sensitive on steep south facing terrain where a stout crust lurks beneath the surface and will provide for a good sliding surface.  We have had several reports of skier triggered avalanches mainly on south aspects over the weekend.  This setup of new snow bonding poorly to crusts primarily exists on terrain over 35 degrees.

Additional Concerns

Persistent Slab
Old wind slabs, formed by strong winds of last Tuesday are lingering below a fresh coating of snow.  These slabs are sitting on weak snow, are somewhat random in their distribution, and concealed by 2-8" of new snow.  Because of this they are hard to detect.  Staying off of steep terrain (>40 degrees) will help to minimize your chances of finding one of these isolated pockets of slab.

Cornices
The most destructive avalanches we have seen over the past three weeks have been the result of large cornice falls.  Minimize your time on terrain with cornices sitting above and approach ridgecrests with caution.


Mountain Weather

In the past 24 hours the mountains around Eastern Turnagain Arm on average have picked up ~6" of new snow with .6" of water.  Temperatures at the Seattle Ridge station at 2,400' averaged 22.5 F.  Winds there have averaged 10 mph out of the ESE with gusts to 22mph.

Light snow continues to fall in the area and should continue through the evening hours with 6-10" expected.  The peak intensity for snowfall will occur in the morning hours today.  Winds will pick back up later in the day and average 15-25mph out of the E.  Temperatures at 1,000' will stay in the high teens to low 20s F today.

The extended outlook calls for clearing on Tuesday with a return to an active (snowy) weather pattern for the second half of the week.

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Wendy will issue the next advisory tomorrow morning, March 26th.

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 06, 2018 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: ClosedClosed as of April 20th
Placer River: ClosedClosed as of April 17th
Skookum Drainage: ClosedClosed as of April 1st.
Turnagain Pass: ClosedClosed as of May 7th. Happy summer, see ya when the snow flies!
Twentymile: ClosedClosed as of April 13th
Seward District
Carter Lake: ClosedClosed as of 4/27
Lost Lake Trail: ClosedClosed as of April 13th
Primrose Trail: ClosedClosed as of April 13th
Resurrection Pass Trail: ClosedClosed as of April 20th
Snug Harbor: ClosedClosed as of 4/27
South Fork Snow River Corridor: ClosedClosed as of April 13th
Summit Lake: ClosedClosed as of April 20th

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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