CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Graham Predeger  
Friday, April 8th 2016
Created: Apr 8th 5:47 am
1 Low Alpine / Above 2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
3 Considerable Treeline / 1,000'-2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
0 NO RATING Below Treeline / Below 1,000'
 Show the Complete North American Avalanche Danger Scale
Alyeska Pipeline Service Company
Special Announcement

The Chugach National Forest will be closing some riding areas to motorized use today due to snow melting out.  Please see the table at the bottom of this page for a complete list.  Snug Harbor, Summit Lake and Turnagain Pass (N. of Granite creek) will remain open. 


The Bottom Line

There is a generally LOW avalanche danger throughout Turnagain Pass for our typical avalanche problems.  The one exception continues to be glide avalanches in the mid-elevation and is why the danger is CONSIDERABLE between 1,000’ and 2,500’ in elevation.  Cautious route finding and terrain evaluation are essential to avoid being under the runout of glide cracks.

*As glide avalanches continue to release, summer use trails with avalanche terrain above should be avoided. The Byron Glacier trail in Portage Valley is not recommended and the Turnagain Arm Trail between Bird and Girdwood, remains CLOSED.


Primary Concern

Glide avalanches continue to be the primary concern in the mid elevations extending as high as 3000'. Many large glides have released this week leaving Turnagain Pass covered in dirty brown streaks.  New glide avalanches were reported in both the Girdwood Valley, Seattle creek drainage and Seattle ridge overnight (see below), leaving us no doubt that this is still a very dangerous avalanche problem.  Seattle ridge just above the Seward highway appears to be the epicenter of Glide activity, and still harbors large cracks that have yet to release.  If travelling in the vicinity of glide cracks today, travel fast and limit your exposure time or better yet, avoid cracks and runout zones all together.

'Repeat Offender' slide path as seen from the DOT RWIS camera this morning.  A large crack failed (and avalanched) overnight near or possibly covering the common snowmachine up-track.  There is still a lot of well-travelled terrain threatened by glide cracks that have not avalanched yet.


Secondary Concern

Warming daytime temperatures and direct sun today will increase the likelihood of wet avalanches in the afternoon below 3,000'.  It’ll be prudent to keep an eye on your boot penetration throughout the day.  Stay off of steep slopes (greater than 35 degrees) where you are post holing up to your crotch.  Boot penetration is an informal test, but it does give a good idea of just how deep the ‘rot’ goes.  Yesterday afternoon, the surface was unsupportable up to at least 2,200’ and likely higher.  Any wet loose avalanches triggered today are likely to be on the smaller scale but could prove troublesome if coupled with a terrain trap.  Formation of fresh roller balls will be a good clue that the surface is losing strength and a good indicator of wet avalanche activity on steep slopes.  

Roller balls forming late in the day often act as a precurser to wet avalanche activity.


Additional Concern

Moderate easterly winds and intermittent snow showers over the last several days have built shallow wind slabs (12-18”) in the alpine.  Given the firm melt-freeze crust deposited to ridgetop last week, these shallow wind slabs have potential to be touchy in steep, unsupported terrain.

Cornices:  They continue to cling to ridges.  Likely triggers today could take the form of skiers, snowmachiners or warming temperatures and direct sun.  Stay well away from the edge of corniced ridges as these have a tendency to break much further back than you may expect.


Mountain Weather

Mostly clear skies graced the eastern Turnagain arm region yesterday with temperatures averaging 38 degrees at Center ridge (1,880’).  Winds were light for most of the day and transitioned to outflow (WNW) by mid-morning.  No new precipitation was recorded.

Today patchy morning fog along Turnagain arm and the Portage valley should give way to clearing skies.  Ridgetop winds will be in the 10 - 20mph range from the North before picking up and transitioning to an Easterly this evening with the approach of our next weather disturbance overnight and through the weekend.  Temps today are expected to be in the 35 -40 degree range at 1,000'.  No new precipitation is expected today though it looks like a return to a showery pattern through the weekend.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 38  116 
Summit Lake (1400') 39   0 35 
Alyeska Mid (1700')  36  0 102 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  27 WNW  21 
Seattle Ridge(2400') 31  WNW   22

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