A buried surface hoar layer beneath today's new snow, ranging from 22 to 40+ cm deep, is causing hair-trigger instability. Any steep slope is very likely to release a slab avalanche. Though the slabs we triggered were small, light, and shallow, additional snow and wind loading may cause much larger slides with potentially serious consequences.

In our tests, a fracture streaked across all the blocks as we dug on a 42° slope, and part of our test block array and the adjacent slope slid off as a small slab avalanche on the surface hoar layer. Since the slab moved on all three blocks, we rated all as #1 releases, while digging or cutting (AK1Q, CAK1Q2, RB1Q2).

All three blocks also released at #6, multiple hard jumps, on the 126cm layer, a density and hardness change with some possible faceting (AK6Q, CAK6Q2, RB6Q2).

The deeper weak layer poses little problem unless more load causes slides to step down to it once they are moving.

We rated the strength -, the stress -, the energy -, and the structure -, where + indicates greater snowpack stability, - lesser, and ~ neutral. This is a grand slam for weakness, slabs are very likely to release.

The new powder snow is very nice riding and is deep enough that it requires at least a 25° slope angle to move fast enough for turns on skis, so it is likely that snow-hungry riders will be lured onto steep slopes this week, a dangerous combination of snowpack and human factors.

Though the slabs are small and light now, they could rapidly become dangerous if loading from new snow or wind continues. Keep your slope angles down, avoid any heavily loaded areas, and travel using maximum risk reduction procedures like having only one person on the slope at a time. Resist the temptation of those who have been long-starved for snow to just dive in without evaluation.