Next week's deep snowpack structure?

We dug a pit on Saturday up at Yodelin on a north-northwest facing slope in mature forest. There was a shallow layer (~10 inches deep) that took an elbow swing to release. There was another layer at 3 feet that I couldn't get to release even with a full arm swing. However, the two foot slab above it did break out cleanly with a shovel pry behind the slab. I'm planning on keeping an eye out for that layer since it may be weaker elsewhere.

Another observation: the snow in the mature forest was more consolidated (and less fun to ski) that the snow in the younger forest (former clear cuts). Normally I would expect the snow in the mature forest to be better shielded from solar radiation and wind and generally less consolidated, but this was not the case. Given the numerous large tree bomb craters (up to 6-ft in diameter) in the mature forest I postulate that the impact of the tree bombs tend to consolidate the nearby snow. Has anyone else seen this effect?

Given all the Internet attention to the "unstable deep layers", I am staying off anything over 55 degrees for the present.

Radical prudence, Tim! But did you send Silas out to probe such slopes this past weekend?

ScottK - I have not done a scientific analysis of any sort, but I certainly have observed the tree bomb cycle many times in mature forest, and have to believe that it has an impact on reducing overall tension in the snowpack (lots of hard strikes, some breaking up of larger "sheets") as well as in providing a better anchor for the next bit of snow to fall (i.e. a very rough surface for the next layer to sit on top of - perhaps somewhat tempered by the slipperyness of the ice caused by tree pee, though...).

Trumpetsailor - regarding the open slopes, I of course agree with the "read the forecast" comments (and I'm no expert - just another duffer out trying to have fun and stay alive), and tend to look both in there and in the wild for any evidence that I should have heightened concern about layers beneath the latest significant crust. This past weekend, it did not appear (below 6K in Snoqualmie area) that we needed to have exceptional concern about lower layers. That said, we did follow avy protocol both going up and down (uptrack crossed a few steeper slopes which we took one at a time, watching from safe zones, same deal on way down). I realy like to repeat a familiar tour many times throughout the winter and do several little and easy stability tests on the way up and down (on way up, pole basket probing, finding steep unsupported rolls on different aspects to jump on - of course to your point, the value of these goes down a bit the deeper a layer you're concerned about..., on way down ski cuts and pits depending on concern and slope of interest) - while not foolproof, they do seem to give some good relative feedback about what's going on which helps augment what I read in the forecast (and subseuqnetly see in other reports from the same day which give a hint at just how unstable the day really was) - all about trying to calibrate myself somewhat. Depending on my concern level, I will prefer open slopes that are somewhat broken into chunks versus one huge open drop - better to have a smaller slope let lose than a massive one (but that's of course true any time you have any level of concern).

We dug a pit on Saturday up at Yodelin on a north-northwest facing slope in mature forest.  There was a shallow layer (~10 inches deep) that took an elbow swing to release.  There was another layer at 3 feet that I couldn't get to release even with a full arm swing.  However, the two foot slab above it  did break out cleanly with a shovel pry behind the slab.   I'm planning on keeping an eye out for that layer since it may be weaker elsewhere.

Another observation: the snow in the mature forest was more consolidated (and less fun to ski) that the snow in the younger forest (former clear cuts).   Normally I would expect the snow in the mature forest to be better shielded from solar radiation and wind and generally less consolidated, but this was not the case.  Given the numerous large tree bomb craters (up to 6-ft in diameter) in the mature forest I postulate that the impact of the tree bombs tend to consolidate the nearby snow.  Has anyone else seen this effect?

Yodelin during a heavy wind gets LOTS of tree-bomb consolidation, in my experience. I think your postulation might be correct...

Thanks for sharing the conditions info -- maybe I missed it, but did you post a TR? I'd encourage you too, even if it's duplicative. The more folks we have sharing their findings in the trip reports section (where most folks look for them), the better informed we'll all be. The conditions you found at Yodelin sound a lot like what we found at Skyline, across the highway.