CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Wendy Wagner  
Sunday, January 29th 2017
Updated: Jan 29th 10:38 am
Created: Jan 29th 5:19 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.
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
Special Announcement

Dangerous avalanche conditions exist in many areas around Southcentral Alaska
including the Southern Kenai Mountains, Hatcher Pass and Anchorage Front Range

  • There was a confirmed snowmachine triggered avalanche accident in the Snug Harbor area yesterday that resulted in a fatality, limited information exists and we are gathering details currently. Our thoughts are with the family and friends.
  • The Southern Kenai Mountains, including Snug Harbor and Lost Lake zones have dangerous avalanche conditions. This region is out of the advisory area but received 3-5+ feet of snow in the past week and several avalanches have been observed. 
  • Click HERE for the Hatcher Pass Avalanche Center advisory and HERE for recent snowpack observations.


**Wherever you decide to venture today with the clearing skies remember: Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential. Carry your rescue gear and practice safe travel protocol - such as exposing one person at a time, grouping up in safe zones, having escape routes planned and watching your partners!  Sticking to slopes under 30 degrees with nothing steeper above you can make for a safer day enjoying the new snow.


The Bottom Line

There is a CONSIDERABLE avalanche danger above treeline in the mountains surrounding Turnagain Pass, Placer Valley and Johnson Pass. Human triggered slab avalanches 2-4' in depth are likely in areas that have seen little traffic (prior to last week's storms) and where a shallower snowpack exists (such as the South end of Turnagain Pass). These could be large and dangerous slides that break near the ground. These are the types of slabs that can be triggered remotely, meaning from the bottom/mid-slope or adjacent to the slope. In the trees, a MODERATE danger exists where triggering one of these slabs is possible. Below 1,000' the danger is LOW where wet snow has now frozen into a hard crust.

Girdwood Valley:  Human triggered slab avalanches have the potential to be larger, and break near the ground, compared to Turnagain Pass due to more snow that has fallen on a weaker snowpack. 

Summit Lake: Dangerous avalanche conditions exist. Please check out the Saturday Summit Summary HERE

 


Primary Concern

Cooling temperatures and clearing skies are a welcome relief to the overcast and low visibility conditions the past week. These better weather conditions will also allow for travel above treeline into the upper elevations - where the best powder exists from the past storms - this combination is our main concern at the avalanche center. Simply put, the snowpack is unstable in many areas and today could be a good day to get lured into steep avalanche terrain sporting good snow. What we have is a slab 2-4' thick composed of last week's storm snow (Jan 21 and Jan 26 storms). This slab sits on a variety of weak layers, most pronounced in the Girdwood Valley and the Southern end of Turnagain Pass, and further South. Several observers have noted widespread collapsing in the areas South of Turnagain Pass.

Careful snowpack evaluation is key today:

  1. Listen for whumphing (collapsing of the slab)
  2. Watch for cracks that shoot from your snowmachine, skis or snowboard
  3. Do you see any recent avalanches? 
  4. Can you feel weak sugary snow when you step down with your boot? Possibly not if the slab is 2-3' thick where you are
  5. Is the snowpack thin in general? 

These are all good questions to be asking yourself. Keep in mind, these signs may not be present, especially in areas well traveled prior to the storms, but don't let that sway you into thinking the steeper slope next door and less traveled is safe. Today could be a tricky day to truly assess if a slope will slide or not. Due to the potential for large un-survivable avalanches, hedging your bets and sticking to mellow slopes is recommended.

A couple other points to consider:

  1. Hand pits may not work as the slab is likely too thick
  2. Slope cutting and ski cutting is not recommended as the slab may break above you
  3. Remote triggering is possible (from below, mid-slope, adjacent to or from the ridgeline)

Low visibility and a thin snowpack exist on Magnum's West face


Additional Concern

Cornices have grown substantially with the Jan 26 warm storm. These could be teetering on the balance and if one breaks, is likely to trigger a potentailly large slab avalanche below. Please be careful along ridgelines as a cornice break could not only take you down, but a subsequent avalanche could overrun someone below you.


Mountain Weather

Yesterday's weather consisted of overcast and obscured skies with light snow flurries. Snow accumulation was a trace to 3" depending on locations. Temperatures continued to be warm, in the upper 20's to 30F in most locations. Winds were light with gusts into the 20'smph from the Northwest.

Overnight, skies have cleared and temperatures have dropped dramatically with a cold Northwest flow over the region. Currently temperatures sit in the single digits above 3,000' and in the teens below this, where they are expected to remain today. Ridgetop winds are, and will be, light to moderate from the Northwest (5-15mph) with gusts into the 20-30mph. There is no precipitation expected and skies should be partly sunny. 

Tomorrow and Tuesday another system will move through bringing a chance for additional snow and warming temperatures before a possible dry spell for the later part of the work week. Stay tuned.

 

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880') 21  0.1  62 
Summit Lake (1400') 17  26 
Alyeska Mid (1700') 21  trace  0.02  54 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812') 13  NW  24 
Seattle Ridge(2400') 15  Rimed  Rimed   Rimed

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