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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Friday, February 6th 2015
Created: Feb 6th 6:23 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
0 NO RATING Below Treeline / Below 1,000'
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Alyeska Resort
Special Announcement

Attention Ladies: SheJumps, CNFAIC, and Alyeska Resort are joining forces to host a 2 hour avalanche companion rescue clinic at Alyeska Resort on Sunday, Feb.8 from 1pm-3pm. This is a free clinic for ladies only, and is a great place to practice your beacon skills. Click HERE for more info.


The Bottom Line

Pockets of MODERATE avalanche danger are possible today within a mostly LOW danger snowpack. Chilly Northeast winds are expected to blow 15-30mph through today increasing the potential for shallow (5-8”) wind slabs on steep leeward terrain features above 2000’. These winds slabs are unlikely to bury a person, but could be enough to knock you over and take you for a ride. Avoid steep terrain if you see shooting cracks or hear hollow sounding snow.

In the Girdwood area, just outside of this advisory zone, there is a little more uncertainty about the snowpack at higher elevations above 4000’ and thus more potential for an overall MODERATE danger rating in the Alpine. A weak layer sitting on a bed surface has been found within the top 12” of the snowpack above 4000’ and wind loading today could make this layer more reactive. 


Primary Concern

A high wind warning has been issued for Thompson Pass and the Matanuska Valley as a tight pressure gradient forces cold Northern air through the Southcentral region. Luckily for Turnagain Pass and Girdwood we are slightly sheltered from this predominant Northeast flow, and winds are only expected to reach 20-30mph today along ridgetops. However the wind chill factor could be as low as -20F with temperatures expected to dip into the single digits (F.)

For Turnagain Pass this does not fair well for the overall skiing and riding quality we’ve been enjoying for the last two weeks. 2-6” of poorly bonded surface snow sitting on a firm bed surface below is likely to blow around today, and could form isolated shallow wind slabs up to 8” thick. These wind slabs could be triggered on the leeward side of steep terrain features and will be of most concern in high consequence terrain where taking a fall could cause injury. Avoid pillow-like features on steep terrain and pay attention for obvious signs of a tender wind slab like shooting cracks and hollow sounding snow. 

Girdwood Valley

In the Girdwood Valley facets forming under a crust have been found within the first 12” of the snowpack between 4000’ and 5000’, and has shown some propagation potential in test pits. This weak layer is sitting on a firm bed surface could become more sensitive today with wind loading. This is an additional reason to avoid steep terrain. This is slightly outside of our normal forecast zone, but is worth pointing out since so many people have been getting high into the Alpine over the last week. 


Additional Concern

Frost Bite

Today might be a pretty uncomfortable day if you choose to venture into the mountains. With temperatures expected to dip into the single digits and winds forecasted as high as 30mph, the wind chill could reach -20F. Dress appropriately and remember to keep your face and extremities well insulated and covered. 


Mountain Weather

Yesterday skies were clear and the inverted air kept temperatures in the single digits (F) near sea level and temperatures reached 20F along ridgetops. Winds were light out of the East with and no new precipitation recorded for almost a week.

As of this morning the ridgetop winds out of the Northeast in Girdwood have increased into 20’s (mph) along ridge tops – this is the first sign of sustained moderate Northeast winds forecasted for today. A high pressure over the interior and low pressure in the Gulf of Alaska is causing a tight pressure gradient over the Copper River Basin. A high wind waning has been issued for Thompson Pass and the Matanuska Valley. Northeast winds are expected to be 20-30mph hour today through Turnagain Pass and Girdwood. Temperatures will be in the teens to single digits F. This could produce a wind chill as low as -20F along ridgetops. Skies will remain sunny and clear and no new precipitation is expected with the arrival of this wind event. 

Sustained Northeast winds up to 30mph are expected to last through Saturday with temperatures remaining in the single digits (F.) Clear skies will become partly cloudy Saturday night into Sunday. There is a hint of a pattern change happening early into the week with a possibility of snow.     

*Alyeska Midway Weather Station data only available from 7am-11am on Feb.5,2015

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 11  31 
Summit Lake (1400')
Alyeska Mid (1700') *9  *0  *0  *21 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  15 Var.  20 
Seattle Ridge(2400') 14  12 

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: Apr 28, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: Closed
Placer River: Closed
Skookum Drainage: ClosedSKOOKUM DRAINAGE CLOSED TO MOTORIZED USE ON APRIL 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: OpenOpen thru May 14th.
Twentymile: Closed
Seward District
Carter Lake: OpenClosed May 1.
Lost Lake Trail: OpenClosed May 1.
Primrose Trail: OpenClosed May 1.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: OpenClosed May 1.
South Fork Snow River Corridor: OpenClosed May 1.
Summit Lake: OpenClosed May 1.

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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