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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Thursday, March 1st 2012
Created: Mar 1st 6:58 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
3 Considerable Below Treeline / Below 1,000' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
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The Bottom Line
Good morning. This is Wendy Wagner with the Chugach National Forest Avalanche Information Center on Thursday, March 1st at 7am. This will serve as 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).

BOTTOM LINE
The avalanche danger will rise to CONSIDERABLE today for storm snow instabilities with new snow and wind arriving currently. Wind slab avalanches will be the most dangerous problem today and these will likely to be triggered by a person on slopes steeper than 35 degrees with recent wind deposited snow. In areas out of the wind below treeline, a MODERATE danger exists for loose snow avalanches on the steeper slopes.

AVALANCHE DISCUSSION
Calm weather at most locations yesterday allowed for anCNFAIC Staff good day of riding on Sunday/Monday's soft settled powder. Easterly winds, ahead of today's storm, did pick up slightly on the upper ridgelines and in some locations were able to transport snow into soft sensitive wind slabs; foreshadowing today's wind slab problem. We ran into one of these very touchy slabs yesterday on the southern end of Turnagain Pass. Hence, winds will be the big player in increasing the avalanche danger for today.

Primary concern:
Wind slab avalanches. Though we have only 4-8" of snow on tap, there is 12-18" of light powder sitting on the surface that is just waiting for a bit of wind to blow it around. This large source of "available snow for transport" will allow for slabs to form that could be quite deep in certain areas and unmanageable. Adding to this, the winds are expected to average around 35-45mph - right in the "optimal range" for wind slab formation.

These fresh wind slabs are likely to be quite sensitive as they are sitting on loose weak snow. Steering clear of wind drifted areas (e.g., stiff and hollow feeling snow) as well as areas where cracks shoot out from you snowmachine, board or skis is advised. Also, keep in mind Cornices continue to grow and teeter on the brink of failure.

Secondary concern:
In areas without wind effect, loose snow avalanches, or sluffs, are expected to be easy to initiate with the continued new light snow over the existing loose snow on the surface. These continue to have the potential to run fairly quickly and far and will be able to entrain a lot of snow.

Last, we have seen a sun crust that formed two days ago. It seems to be scattered along southerly aspects and not widespread. However, this can provide a good bed surface for an avalanche initiated in these areas to run further and faster than expected.

MOUNTAIN WEATHER
It was anCNFAIC Staff mostly calm, but somewhat cloudy, day in the backcounty. Low clouds inhibited visibility but a few windows did open up. Easterly winds were light with moderate gusts to 15-20mph on the exposed ridges. Light snow added anCNFAIC Staff 1-2" in many places and temperatures were in the upper teens near treeline.

Today we have a front marching in from the southeast associated with a low pressure system spinning over the Aleutian Islands. Strong easterly winds averaging around 35-45mph with gusts over 50mph are expected. Light snow is falling currently and should increase through the day with 4-8" of accumulation expected - possibly more above treeline. Temperatures look to be in the teens at the mid and upper elevations and in the mid to upper 20's in the lower elevations. Snowfall and winds are likely to decrease tonight but light snow should continue into tomorrow.


CNFAIC Weather Page and the NWS forecast


Kevin will issue the next advisory Friday morning. If you get out in the backcountry we want to know what you are seeing. Please send us your observations using the button at the top of this page or give us a call at 754-2369. Thanks and have a great day.

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: Dec 08, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: Closed
Turnagain Pass: ClosedRain and snow have fallen in Turnagain Pass this week, but not enough to open for snowmachining. Continue to check back to this site for updates.
Twentymile: Closed
Seward District
Carter Lake: Closed
Lost Lake Trail: Closed
Primrose Trail: Closed
Resurrection Pass Trail: ClosedResurrection Pass trail is expected to open to snowmachine use during the 2017/18 winter season.
Snug Harbor: Closed
South Fork Snow River Corridor: Closed
Summit Lake: Closed

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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.


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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