CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, February 17th 2013
Created: Feb 17th 6:49 am
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.
 Show the Complete North American Avalanche Danger Scale
The Hoarding Marmot
The Bottom Line

The avalanche danger will be on the rise today as another round of snow and wind moves through the Eastern Turnagain Arm. By this afternoon, the expected 8-12” of new snow with strong wind will bump the danger to CONSIDERABLE above treeline and MODERATE below treeline. Wind slabs 1-2’ deep and storm slabs 6-12” deep, along with loose snow avalanches, will be the main problems to watch for. These will be possible to trigger on all aspects below treeline and become much more likely to trigger above treeline. There is also the possibility for these to release naturally at the upper elevations.


Primary Concern

Another shot of snow and wind has moved in overnight covering the clear skies and great riding and skiing conditions that many folks found yesterday. This new system is taking center stage but we did get some great footage of the natural cycle that occurred 2 days ago in the Valentine’s Day storm snow. Check out the many observations/photos sent in on our observations page.

By 6AM this morning we have picked up 3-4” of low density snow and another 5-10” is forecast to be on the way. This is coming in with strong east winds and slightly warming temperatures. Storm snow avalanches will be our primary concerns. These include shallow storm slabs, larger wind slabs and fast running loose snow sluffs.

Wind slabs will be the most concerning and likely to be fairly sensitive to human triggers as they are sitting on colder weaker snow. There is ample existing snow available for transport (yesterday's cold powder) to build 1-2' think slabs even if new snow amounts are less than expected. Near and above treeline elevations began seeing wind transport yesterday afternoon and these have only grown as winds have increased since then. Watching for areas with stiffer wind deposited snow and cracking in the new snow around you will be clues you have found a slab. These are most likely to be found on rollovers, off ridgelines and in cross-loaded gullies.

Below is a photo from yesterday's east wind hitting Grand Daddy Peak producing a plume blowing snow low onto its western face.

Below treeline: Keep an eye out for winds to penetrate below treeline and build shallow touchy wind slabs. Loose snow sluffing on slopes steep and long enough will also be likely as this storm is colder with snow to sea level.


Secondary Concern

We continue to find a variable and concerning mid-pack snow structure at the mid elevations between 1,500’ and 2,800’. This is more pronounced in the Girdwood Valley. Buried 2-4’ deep now is a thin layer of weak snow sitting on a crust formed in late January. We have yet to see any avalanche activity on this crust in the Turnagain area but there has been some in the Girdwood Valley during the past week. Our pits are telling us this interface is fairly hard to trigger but it is present in the Pass. As more snow loads slopes with additional weight the potential exists for a deeper and more dangerous avalanches to occur at mid-elevations. If you haven’t already done so, check out Graham’s video from yesterday.


Mountain Weather

Yesterday’s window of opportunity – sun, light east wind and temps in the teens – was a bit too short lived for many folks. Currently, a low pressure system is moving up the western Gulf bringing another quick shot of snow as well as a Winter Weather Advisory from the NWS.

Today, we are looking at snow totals of 8-12” by this evening with strong easterly winds. The flow is cold enough that snow should fall at sea level. We have picked up around 3-4” so far by 6am this morning. The associated east winds ramped up to the 30’s with gusts to 60mph overnight and will fluctuate near here for the first part of today before tapering off by noon.  Temperatures are climbing from the teens to the low 30’s at sea level to the upper teens at the ridgetops.

Tomorrow, the remnants of this system look to clear out with a break in clouds, precip and wind. Another low pressure moves into the Gulf on Tuesday as our active weather pattern continues.

 


 

Fitz will issue the next advisory tomorrow morning, February 18th.

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
© 2017 Chugach National Forest Avalanche Information Center. All rights reserved.
FCNFAIC