Turnagain Pass RSS

Archives
ARCHIVED - Forecasts expire after 24 hours.
Issued
Fri, January 6th, 2017 - 7:00AM
Expires
Sat, January 7th, 2017 - 7:00AM
Forecaster
Wendy Wagner
Avalanche risk The Bottom Line

A MODERATE avalanche danger exists on steep terrain above the trees where winds have loaded slopes. Although the very strong winds have blown much of the snow away, expect to find shallow wind slabs that formed off ridgelines and lower on slopes. Watch for any steep slope that harbors recent wind deposited snow. Additionally, these wind slabs may overload buried weak layers and triggering a larger and more dangerous hard slab avalanche exists.  

Lower elevations that have escaped the winds, along with upper elevation slopes that are wind scoured, have a  LOW avalanche danger where triggering an avalanche in unlikely.

Special Announcements

UPCOMING EVENTS:

  • Join CNFAIC and AMDS at the Turnagain Pass motorized lot this Saturday at 10:30am for a “passing off” of the keys celebration (keys to a brand new 2017 Ski Doo Summit SP 850)! HUGE thanks to AMDS and BRP/Ski Doo for granting the Friends of the CNFAIC a new loaner snowmachine for the season!! Stick around for a quick state of the snowpack discussion after!
  • Discussion on Backcountry RESCUE presented by team members of the U.S. Air Force 212th Rescue Squadron (RQS/PJ’s) and Alaska Mountain Rescue Group (AMRG). Details HERE!
  • 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.

Fri, January 6th, 2017
Alpine
Above 2,500'
2 - Moderate
Avalanche risk
Treeline
1,000'-2,500'
1 - Low
Avalanche risk
Below Treeline
Below 1,000'
1 - Low
Avalanche risk
0 - No Rating
1 - Low
2 - Moderate
3 - Considerable
4 - High
5 - Extreme
Avalanche risk Avalanche risk Avalanche risk Avalanche risk Avalanche risk
Travel Advice Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features. Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern. Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding, and conservative decision-making essential. Very dangerous avalanche conditions. Travel in avalanche terrain not recommended. Extraordinarily dangerous avalanche conditions. Avoid all avalanche terrain.
Likelihood of Avalanches Natural and human-triggered avalanches unlikely. Natural avalanches unlikely; human-triggered avalanches possible. Natural avalanches possible; human-triggered avalanches likely. Natural avalanches likely; human-triggered avalanches very likely. Natural and human-triggered avalanches certain.
Avalanche Size and Distribution Small avalanches in isolated areas or extreme terrain. Small avalanches in specific areas; or large avalanches in isolated areas. Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas. Large avalanches in many areas; or very large avalanches in specific areas. Very large avalanches in many areas.
Avalanche Problem 1
  • Wind Slabs
    Wind Slabs
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
More info at Avalanche.org

Very strong “outflow” winds impacted the region yesterday. Cold arctic air rushing down from the North battered the mountains. What soft snow did remain after the Dec 30th wind event was likely taken away with this Jan 5th wind event – a bit like salt on the wound! We only know of one small natural wind slab that released on an Easterly aspect in the Summit Lake area yesterday. Otherwise, there was just too little snow available for transport to produce natural wind slab avalanches. 

For Today:  Watch for new wind slabs from yesterday, overnight and today (winds are forecast to be moderate from the North and West). These slabs are likely to be shallow, very stiff and could surprise you on a steep slope. Watch for these in any location with wind loading, including lower on slopes. These also have the potential to overload buried weak layers and produce a much larger and dangerous avalanche. The Easterly face of Seattle Ridge is an example of where winds have been loading and known buried weak layers exist.

Safe travel protocol is your friend and if you head out today, remember to expose one person at a time, watch your partners, have an escape route planned and group up in safe zones.

 

Significant wind transport along Wolverine Ridge (seen from Portage). Winds along this ridge were more Southwesterly due to “terrain forced flow” in complex topography. 

 

The Summit Lake and Kenai Mountains got hit as well with these impressive winds. Below are plumes coming off the Southwest shoulder of Silvertip Peak (far left). 

 

Avalanche Problem 2
  • Persistent Slabs
    Persistent Slabs
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
More info at Avalanche.org

Although the snowpack is wind hardened and tired, it does have a poor structure. There are a variety of weak layers in the middle of the pack as well as at the bottom. The slab on these weak layers is quite variable and hard – and though difficult to trigger, the possibility does exist. Steep wind loaded slopes (Northern and Eastern) that haven’t avalanched yet are the most suspect. Likely trigger spots are in thinner areas near rocks. Obvious signs like cracking and ‘wumpfing’ are becoming less common, making it more difficult to assess slope stability. Heavier loads, such as snowmachines or large groups of people can also be a trigger. 

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. 

Additional Concern
  • Glide Avalanches
    Glide Avalanches
Glide Avalanches
Glide Avalanches are the release of the entire snow cover as a result of gliding over the ground. Glide avalanches can be composed of wet, moist, or almost entirely dry snow. They typically occur in very specific paths, where the slope is steep enough and the ground surface is relatively smooth. They are often proceeded by full depth cracks (glide cracks), though the time between the appearance of a crack and an avalanche can vary between seconds and months. Glide avalanches are unlikely to be triggered by a person, are nearly impossible to forecast, and thus pose a hazard that is extremely difficult to manage.
More info at Avalanche.org

Believe it or not, 3 glide avalanches have occurred in the past 5 days in the Turnagain Pass zone. These are SE aspect of Lynx CreekSE aspect of Seattle Creek, and the SW face of Eddies. Along with recognizing wind affected snow, keep an eye out for glide cracks and limit time under these. They can have a knack for releasing during cold weather.

Weather
Fri, January 6th, 2017

Extremely strong Northerly winds impacted the Southcentral mountains yesterday. Skies were mostly clear, but winds were averaging as high as 54mph with gusts to 79mph. These winds brought temperatures down to ~10F on the peaks but scoured out the cold air in the valleys where temperatures rose to the upper 20’sF.

Overnight we have seen decreasing winds, but we are still expecting the North flow to be moderate – averages 10-15mph with gusts into the 30-40’s. Temperatures should remain chilly, 10-15F at most elevations and valley bottoms. Skies look to be mostly clear today.

It seems as though the blocking area of high-pressure over mainland Alaska will persist into next week. Along with this will be clear skies, cold temperatures and no expected precipitation.

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 19   0   0   35  
Summit Lake (1400′) 21   0   0   11  
Alyeska Mid (1700′) 20   0   0   23  

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  12 NW   11   63  
Seattle Ridge (2400′)   16   N   38   79  
Observations
Recent Observations for Turnagain Pass
Date Region Location
05/13/24 Turnagain Observation: Eddie’s, Sunburst, Seattle, Cornbiscuit, Pete’s South
05/13/24 Turnagain Observation: Turnagain Pass non-motorized side
05/12/24 Turnagain Observation: Warm up Bowl
05/07/24 Turnagain Observation: Turnagain Pass Wet Slabs
04/29/24 Turnagain Avalanche: Turnagain aerial obs
04/27/24 Turnagain Observation: Johnson Pass
04/23/24 Turnagain Observation: Turnagain Sunny Side
04/21/24 Turnagain Observation: Bertha Creek
04/20/24 Turnagain Avalanche: Spokane Creek
04/16/24 Turnagain Observation: Cornbiscuit
Riding Areas

The riding areas page has moved. Please click here & update your bookmarks.


Subscribe to Turnagain Pass
Avalanche Forecast by Email

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.