Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Lots of wind affected snow around, but no significant signs of instability observed even on wind-loaded test slopes.

On a wind loaded SW facing test slope at 5900' I was unable to produce significant shooting cracks. I did observe a small crack below my skis, but this didn't extend beyond the area directly affected by my skis. On this same slope a shovel tilt test failed to produce a failure, but it was possible to shear away a layer ~20 cm deep cleanly by hand.

A pit in a sheltered area on the East aspect of Mazama ridge at ~5800' (20-30 feet below ridge crest) revealed a similar layer ~13cm deep that produced a failure in two column tests, CTM12 and CTM11, but did not propagate across an extended column, ECTN12. I was unable to produce results around the crust at 43 cm or the layer at 33 cm from the first storm after the rain.

Similarly on a NNE aspect with some evidence of fresher Wind loading from a local Southerly wind at 5800' I dug to the crust and found a similar layer (15-20cm) that reacted similarly to a hand shear - a clean fracture, but fairly stubborn. I was unable to produce a clean fracture in the 10-15cm above the crust in this location which was still showing a bit of surface hoar mid-afternoon on Saturday.

On the West facing slope of Alta Vista at 5800' I was unable to produce any fractures in a hand shear down to the rain crust. At this location, the crust was only ~30-35 cm deep.

There were plenty of signs of wind effect with stiff, textured snow, ski penetration in the 1-3 cm range pretty widespread with a predominantly westerly wind direction. The wind effect extended pretty far (easily 150') below the ridge on the West-facing slope entering the bowl near the North end of Mazama Ridge.