Professional Observation

Observation Details

Signs of Unstable Snow

Intense drifting snow at all elevations once winds shifted NW and increased after 10 am. Triggered a few small soft wind slabs on test slopes. These were 10 inches (25 cm) thick below 9000 feet and up to 2 feet (60 cm) thick near my high point of 9600 feet.

Key Points

I took a long flat tour and avoided overhead hazards on the moraines in Bishop Creek to see wind slab distribution and sensitivity as winds shifted today.

•  I got some isolated shooting cracks in 8-inch thick, soft wind slabs that had been deposited by previous south winds. As I got above 9000 feet wind slabs were still soft, but up to 2 feet thick. They were reactive under my skis on a north-facing test slope at 9500 feet.
• Winds shifted to the northwest and increased at all elevations after about 10 am. I found ski penetration of up to 30 cm and foot penetration of up to 70 cm through fist to 4-finger hard recent snow on flat and sheltered northwest-facing slopes. The north wind was efficiently transporting it onto southeast aspects. Even after only an hour or two of new drifting, I got shallow cracking around my ski on southeast slopes. New slabs were forming atop hard wind crusts and soft, older, cross-loaded wind slabs.
• Poor visibility and bitterly cold wind chills made for challenging travel conditions. I returned to the car wearing both of my puffies and even my down over-shorts.
• I took a drive up 395 to look for recent avalanche activity in the afternoon but gave up near Crowley because west-to-northwest wind and intense blowing snow were obscuring the mountains at all elevations and causing drifting across the highway.