Blues

New snow will make human-triggered avalanches possible on all aspects at upper elevations.  These problems can change hourly, so evaluate snow and terrain carefully.  Rapidly warming temps, blowing snow or winds strong enough to sway small trees are reasons to seek sheltered terrain under 30 degrees.  

The danger may rise in the evening with increased temperature or winds.  

This forecast is sponsored by: La Grande Sno-Drifters | La Grande OR (facebook.com)

What happened: 

• Yesterday, our party in the Southern/Western Wallowas saw at least 4 natural soft slab avalanches from 12/31 day or New Year's Eve night.   These were on a variety of aspects at middle and upper elevations and mostly 6" thick.  We intentionally triggered a small soft slab (6" thick) in the storm snow.  We also saw shooting cracks, a sign of this instability.  Reactivity decreased by afternoon.  
• Thank you to observers who reported from earlier this week.  As Caleb said, each time a layer of weak snow receives a new load, an opportunity arises to learn more about whether it is gaining strength, losing strength, or staying the same.  Taking advantage (and photos) of good visibility on Monday and Tuesday was helpful to see whether the 2-3' of new snow 12/26-12/30 was enough to overload our Thanksgiving Drought Layer (TDL) and cause natural avalanching.  Seeing a lack of avalanches in observed terrain is significant!  Avalanches reported were in the new snow rather than taking out most of the snowpack on the old snow TDL with crowns 3-4' thick.  Along with a lack of test results on this layer yesterday, this leads us to consider the TDL dormant, but we will continue to monitor it.  

What to expect:  

• Along with storm slabs, you could also encounter windslabs at higher elevations, especially late in the day and especially in the Northern Wallowas where Moderate winds are predicted.  Abundant soft snow is available for transport, as evidenced by boots sinking in up to the thigh.  Wind can move snow to depths 3-5x deeper than non wind-effected areas.   For instance, 4" of soft snow becomes a 12-20" thick windslab, a dangerous avalanche if triggered.  Look for smooth or rippled texture or hollow, drum-like sounds to indicate wind deposited snow.  
• In some places, new snow may not have settled into slabs.  If you are unable to pick up or pull off a block of surface snow (a slab), you are finding potential for loose snow avalanches.  Dry loose avalanches can run far and knock you off your feet.  

What to do:

• When finding new snow problems, you can use your hand to isolate a block of snow about 1' by 1' and pull it downhill.  If it comes off as a cohesive block instead of crumbling, you have a slab and can estimate it's thickness.  Look at the steep slope you were about to slide or ride across and anticipate what it would do if it avalanches.  This is a quick, non-standardized test, so do this continously through they day as you move through terrain.   
• Utilizing small and inconsequential test slopes, no taller than a 1 story house, are a good way to test for reactivity in new snow problems.  Using good travel protocols, considering the consequences of each terrain feature, exposing one person at a time, and regrouping in safe zones are important to practice each day if you choose to enter avalanche terrain.  

Riding quality is excellent, hope you are able to enjoy it.  

If you are out in the backcountry, please submit an observation to help us reduce uncertainty.