CNFAIC LogoCNFAIC Logo

Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   Aleph Johnston-Bloom  
Saturday, January 28th 2017
Created: Jan 28th 4:20 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
Alyeska Resort
Special Announcement

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

  • Click HERE for the Hatcher Pass Avalanche Center advisory and HERE for recent snowpack observations.
  • The Southern Kenai Mountains, including the Lost Lake zone are expected to have dangerous avalanche conditions today. This region is out of the advisory area but received 3-5 feet of snow from last Saturday's storm and received additional snow this week. There were several avalanches observed over the past weekend in that zone and more are possible today. Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!!

The Bottom Line

The avalanche danger is CONSIDERABLE on upper elevation slopes where triggering an avalanche on a persistent weak layer or a wind slab 2-3' thick is likely and cornices are suspected to have grown large and be tender. Careful snowpack evaluation, cautious route-finding and conservative decision-making are essential today.  At Treeline and below the danger will be MODERATE where triggering an avalanche on a persistent weak layer will still be possible. Practice safe travel protocols, always carry rescue gear and please let us know what you see out there!!! 

Girdwood Valley: Slabs have the potential to be larger due to more snow that has fallen on a weaker snowpack compared to Turnagain Pass. Avalanches were running to the ground during the storm.  

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

 


Primary Concern

As we got a few patches of visibility over the past two days we have been able to see evidence of the natural avalanche cycle that occurred during the storm and were reminded of the variability of the snowpack across the advisory area. In Girdwood Valley some avalanches were running to the ground on basal facets that formed early in the season. A similar weak layer is also the suspected culprit in a number of large avalanches that ran in the gullys at the southern end of Seattle Ridge.  At lower elevations in Turnagain Pass there were signs that avalanches were running on the January 13th layer of buried surface hoar. All these persistent weak layers still need time to adjust to the heavy load they received and could be triggered today. Shallow areas in the snowpack will be the most likely trigger spots. Be on the lookout for cracking and collapsing and areas where you can feel weak snow below strong snow. Do not overload steep slopes with multiple skiers or snowmachines on the slope at the same time! 

Yesterday at lower elevations it was easy to find the rain/snow line around 1400'. Water had formed two layers below the surface that were slowly cooling and may have formed crusts overnight. If these are solid today the likelyhood of triggering the January 13th buried surface hoar will go down. If the upper snowpack is still wet, persistent slabs may still be possible. 

Seattle Ridge South, both the gully and the face slid. Road obs yesterday showed that most of the gullys in this area slid and some made it all the way to the creek. 

 

Slab in above Tincan Gorge. Supected weak layer Janurary 13th buried surface hoar. Photo: Joe Kurtak

Snowpit on Tincan at 1100', shows the layers of wet snow and the January 13th buried surface hoar

 


Secondary Concern

Strong easterly winds during the storm quickly moved snow, loaded slopes and triggered natural avalanches. Probing around a minor ridge yesterday showed that the winds had definitely redistributed snow. The windward side had less than a meter of snow and leeward side had over 2 meters. There was wind features in all of the Alpine terrain that was visible. Today wind slabs 2-3' thick are likely on steep leeward slopes. It will be important to look for pillowed or drifted areas and watch for shooting cracks. These slabs may allow you get out onto them before they break. There is still snow available for transport today and the winds are shifting to the west. Pay attention to changing conditions if you see blowing snow and slopes being actively loaded.


Additional Concern

Warm wet snow and strong winds are notorious for cornice growing. We have had limited visibility into the Alpine but suspect they will be looming over much of the leeward terrain. Give cornices wide berth, avoid travel on slopes below and remember they can break farther back onto the ridge than expected.  If they do break and fall they could trigger an avalanche on the slope below.


Mountain Weather

Yesterday was mostly cloudy with snow showers throughout the day. Easterly winds were light with a slight uptick in the evening with gusts in the 20s. Temperatures were in the 30s at valley bottoms and 20s at ridge tops. There was a slight cooling trend overnight. 

Today will remain cloudy with snow showers forecasted throughout the day. Accumulations will be minimal. Temperatures will be slightly cooler than yesterday. Winds will be westerly 10-20 with gusts into the 30s. Snow showers diminish overnight but cloudy skies and a chance of snow remains through the weekend.  

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880')  32  .1  61
Summit Lake (1400')  30  1  .1  27
Alyeska Mid (1700')  30  2  .2 57 

 

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

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812')  21 ENE  10  31 
Seattle Ridge(2400')  24  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