Coming out of a wild week of weather, the snowpack appears to have settled and bonded fairly well. Our biggest concern today is wind slabs, old and new, on Northeast aspects at mid and upper elevation. Persistent weak layers appear to be going to sleep, but don’t take that for granted. Continue to exercise caution in steep unanchored terrain.
Wind slabs will likely form on Northeast aspects below ridgelines and at the tops of chutes, or on cross loaded gullies at mid-elevations.
2” to 6” of new snow forecast for today, paired with gusts out of the southwest up to 30mph, will continue to load wind slabs created during the Christmas storm events. This means new soft wind slabs may form over top of, and mask, older hard slabs.
Weak layers from November and December are now buried deep in our snowpack.
As a forecaster this is a difficult one. While this is becoming increasingly difficult to find and showing little reactivity, the consequences of triggering a 3' deep persistent weak layer would be calamitous. I’m on the verge of letting this one go; but in light of this past week’s wild weather cycles, I still want more field data that shows this problem has gone dormant throughout the forecast zone before I drop it as a problem.
I recommend traveling on slopes <35°, avoid traveling below big convex rollovers and start zones, and be aware of terrain traps like gullies, cliffs and strainers below you.
Yesterday we toured out the Eagle Peak area from Lookout towards Steven’s Peak. The warm temps and infusion of Christmas moisture, followed by below freezing temperatures Wednesday and Thursday nights appear to have firmed up the upper snowpack pretty well. We did not see failures in Extended Column Tests at either of our pit locations.
However, I did find a weak layer buried deep in a heavily wind loaded, near ridgeline, NE aspect slope. It slid dramatically during a Propagation Saw Test. What this tells me is that there continue to be spatial variabilities in the snowpack that are hard to generalize—meaning get out and have some fun, but proceed with caution. Do not assume all slopes are stable just because you find one that is.
Snow and wind from the South thru Southwest today will continue to load North and Northeast aspect slopes on the lee side of ridgelines and on cross loaded terrain. Pay attention to shooting cracks and give cornices a wide berth. A cornice fall or wind slab avalanche could step down into buried weak layers.
How about a New Year’s resolution to practice beacon search and partner rescue? You want those skills to be committed to muscle memory so you can still perform when you are jacked up on fear and adrenaline. All the local resorts have beacon parks now, and I let my kid hide a couple beacons in the backyard for me to find.
Please submit observations. They are really helpful.
Enjoy the new snow and Happy New Year!
