ARCHIVED FORECAST - All forecasts expire after 24 hours from the posting date/time.
Tuesday January 8th, 2019
Posted by Aleph Johnston-Bloom on 01/08/19 at 7:00 am.
Avalanche risk
The Bottom Line
Low Avalanche Danger
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

A generally  LOW  avalanche danger exists across all elevations bands for the Turnagain Area. Triggering an avalanche is unlikely but not impossible. Good travel habits, such as exposing one person at a time, watching your partners and grouping up in safe zones are, as always, key ways to minimize risk.  Ease onto steep slopes and be mindful of people below you and on adjacent slopes. Avoid travel under glide cracks.  

SUMMIT LAKE / JOHNSON PASS / LYNX DRAINAGE:  *** We want to emphasize the difference here! More caution is advised  South of Turnagain Pass.***  Keep in mind buried weak layers exist in the middle and base of the snowpack. More potential for triggering a large slab avalanche exists in this zone. Choose terrain wisely. Please read the Additional Concerns.  

1. Low
Alpine
/ Above 2,500'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1. Low
Treeline
/ 1,000'-2,500'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
1. Low
Below Treeline
/ Below 1,000'
Avalanche risk
Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Special Announcements

Check out our calendar for upcoming avalanche classes and events in January! Lots of opportunities with all the avalanche education providers in the area.  

Avalanche Problem 1
Normal Caution
Normal Caution means triggering an avalanche is unlikely but not impossible.
  • TYPE
    Normal Caution

It has been a week since we had any report of human triggered avalanche activity and observers are not reporting signs of instability. As a mostly calm and cold weather pattern dominates our area and continues until the weekend, we are in the “normal caution” phase of avalanche concerns. These include:

  • Triggering an outlier avalanche. This would most likely be an ‘unsupported slab’ that sits above a cliff or steep rocky terrain. There may still be a pocket of buried surface hoar lurking.
  • Triggering a cornice fall. Remember they break farther back from ridges than often expected. Give them a wide berth.
  • Sluffs on steep slopes. These have been mostly small so far but as the surface becomes weaker the potential will increase. 

Being in the wrong place at the wrong time and getting caught in a glide avalanche also remains a concern. Glide cracks are opening and releasing and have been observed throughout the advisory area in both the Alpine and Treeline elevation bands. It is important to minimize time spent underneath the glide cracks. Release is unpredictable and not human triggered. Be on the lookout for cracks and wrinkled looking snow (often a precursor to cracking). 

Remember LOW hazard doesn’t mean NO hazard! It is still important to look for signs of instability and use good travel techniques.  


Recent glide avalanches and glide cracks opening in Lynx Creek drainage, 1-7-19.

Lipps glide cracks, 1-7-19. 

Additional Concern
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.
  • TYPE
    Persistent Slabs

South of Turnagain – Lynx Creek/Johnson Pass/Summit Lake zone:  A poor snowpack structure exists in these areas. The buried surface hoar that we have been talking about over the past week has been found as well as facet/crust combinations in the bottom of the snowpack. The New Year’s storm overloaded a variety of these weak layers as can be seen in photos from the avalanche activity throughout Summit LakeIf you’re headed this way, the snowpack becomes more complex – evaluate terrain exposure and the snowpack as you travel. 

The facet/crust combination continues to be a layer of concern in Summit Lake. Observers over the weekend found this set-up to be stubborn to initiate but still consistently reactive in multiple stability tests.

 

Mountain Weather

Yesterday:  Skies were clear, winds were light and temperatures were cold. Upper elevation highs were in the single digits to low teens and valley bottom lows were in the negative teens with the inversion. Valley fog conditions persisted. Clouds built in the late afternoon and temperatures increased a little overnight.  

Today:  Is forecast to be partly to mostly cloudy with a chance of snow showers and light southeast winds. Temperatures will be in the teens and low 20Fs. Skies clear again overnight.  

Tomorrow:  Sunshine and cooling temperatures return Wednesday and will be the dominant weather through Friday. Stay tuned for a change over the weekend with a potential return, according to the National Weather Service to warmer, wetter, and  overall more unsettled weather as we  head into next week”.

*Seattle Ridge weather station was heavily rimed and the anemometer (wind sensor) was destroyed. We are currently working to replace it.  

PRECIPITAT

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

  Temp Avg (F) Snow (in) Water (in) Snow Depth (in)
Center Ridge (1880′) 8    0  0  55
Summit Lake (1400′)  -3      0  0   21  
Alyeska Mid (1700′)  5       0    0  45

RIDGETOP 24-hour data (6am – 6am)

  Temp Avg (F) Wind Dir Wind Avg (mph) Wind Gust (mph)
Sunburst (3812′)  10  SW 3   16  
Seattle Ridge (2400′)   11    *N/A *N/A    *N/A