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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Heather Thamm  
Thursday, January 5th 2017
Created: Jan 5th 6:12 am
2 Moderate Alpine / Above 2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
1 Low Treeline / 1,000'-2,500' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1 Low Below Treeline / Below 1,000' Travel Advice: Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
 Show the Complete North American Avalanche Danger Scale
Hidden Creek B&B LLC
Special Announcement
  • We are happy to report DOT was clearing the motorized lot yesterday! They may be working in this area again today, please park out of their way, so the entire area can be cleaned up.
  • There is a Kenai Peninsula Avalanche Information Workshop this Sunday, January 8th at 5:30 pm at the Flats Bistro. Hope to see you there! More info HERE.
  • Its that time of year again, PFD time! If you are feeling generous and want to support your local avalanche center, Pick Click Give, makes it really easy to become a supporting member of CNFAIC.


The Bottom Line

A MODERATE avalanche danger remains in the alpine (all areas above the trees) where triggering a small isolated wind slab is possible today. Triggering a deeper 2+’ thick hard slab will be stubborn to trigger, but not impossible on specific terrain features on North and East aspects that have not avalanched yet. Avoid slopes that have existing glide cracks, these could release to the ground without warning.  Within the trees and at lower elevations there is LOW avalanche danger, where triggering an avalanche is unlikely.

***Today’s cold temps and high winds are going to make travel uncomfortable in the upper elevations; windchill factors could be well below zero. Should you decide to venture into the mountains bring extra warm layers and food. Be sure to practice safe travel protocols by only exposing one person at a time in avalanche terrain and watch your partners from a safe zone. This is not a good day to get injured in the backcountry.

In the periphery zones of Girdwood, Johnson Pass and Summit Lake a much shallower snowpack exists and it may be easier to trigger a slab avalanche in these areas.  Check out the Summit Lake Summary HERE and recent observations from Girdwood HERE.

 


Primary Concern

Today Northwest winds are expected to build this morning, 25-45mph in alpine and gusts in the 60’s mph. By late afternoon gusts could reach 75’s mph. Upper Northwest winds in and around Turnagain Pass can be confusing and can funnel through terrain in a more Southwest direction. Luckily there isn’t much snow available for transport in the upper elevations of Turnagain Pass. The December 30th wind event did a pretty good job of hardening the existing surface. With that said there are still some pockets of soft snow that could be blown around and form small fresh wind slabs today. The places to avoid will be steep exposed terrain where getting knocked off your feet will have high consequences. Also if winds do blow from a more SW direction it may make it easier to trigger and older wind slab 4-10” thick on North and East aspects. Watch for blowing snow along ridgtops and cracking will be an obvious sign these windslab are unstable. It is also possible that a small wind slab could step down into an older deeper layer of the snow pack in certain areas. More details on this in secondary concerns.  

Current surface conditions in the alpine are variable with some pockets of soft snow, but there is not a lot available for transport. Photo taken 1/4/17 on a SW aspect of Tincan.

 


Secondary Concern

Be skeptical of steep loaded (Northern and Eastern) slopes that haven’t avalanched yet. Likely trigger spots will be in thinner areas of the snowpack near rocks or unsupported slopes that may harbor just the right set-up. A 2-3 foot hard slab is sitting on top of very weak snow (facets and buried surface hoar) in these specific areas that haven't avalanched. A persistent hard slab avalanche could be triggered near ridge tops or mid slope. Obvious signs like cracking and ‘wumpfing’ are becoming less common in the Turnagain Pass area and may not be an early warning sign. This problem will be stubborn to trigger, but should you find the right spot the consequence could be very dangerous. As you travel today identify Northern and Eastern aspects that haven’t avalanched. Old debris is still very visible and is a good way to identify if a slope has avalanched or not.

In the periphery areas (Girdwood, Johnson/Lynx Creek and Summit Lake) where a thinner snowpack exists several observers have experienced collapsing/wumpfing in recent days. Including a recent snowmachine triggered slab in Lynx Creek  and widespread collapsing and shooting cracks on Notch Mountain in Girdwood Valley two days ago. It will be in these areas where a persistent slab may be easier trigger.

 

Poor structure (hard 2-3' slab sitting on weak facets) was found yesterday on a loaded North aspect of Tincan and remains a concern on loaded North and East aspects. 

 


Additional Concern

Over the last two days 3 glide cracks have avalanched in Turnagain Pass; one on a SE aspect of Lynx Creek, SE aspect of Seattle Creek, and the SW face of Eddies. Glide cracks release without any warning and are not associated with human triggers. It is best to avoid existing cracks by not traveling under or within the runout of these unpredictable hazards. Should one avalanche this is the entire snowpack releasing to the ground. 

 


Mountain Weather

Yesterday skies were sunny becoming partly cloudy in the afternoon. Winds began to increase from the NW averaging 10-15mph.  A large temperature inversion began to narrow; ridgetops temps dropped from the low 30F’s to the low 20F’s.  Valley bottom temps increased from 5F to 15F overnight. No precipitation has been recorded in the last week. A dense valley fog has been sitting in and along Turnagain Arm for many days. 

Today expect temperatures to slowly drop throughout 10-15F by late afternoon. Moderate Northwest ridge top wind are expected to build by early afternoon becoming strong (25-45mph) with possible gusts in the 60’s mph.  By early evening gusts could reach 75mph. This could bring the windchill factor well below zero (F) today.

A high pressure system is positioned over Southcentral and Interior, Alaska that will keep temperatures cool and skies clear over the coming days. Winds are expected to decrease by tomorrow afternoon in the Turnagain Pass area, and temperatures will continue to drop possible reaching single digits (F.) This pattern is expected to continue through the weekend into early next week.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 24  36 
Summit Lake (1400')  17 11 
Alyeska Mid (1700')  19 23 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  22 WNW  27 
Seattle Ridge(2400') 25  WNW  12  42 

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

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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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