Collapsed Surface Hoar, Tender Cornices, and Lingering Wind Slabs on Judah

Location Name: 
Mt. Judah
Donner Summit Area
Date and time of observation: 
Sun, 01/28/2018 - 12:30
Location Map: 
United States
39° 18' 23.22" N, 120° 19' 1.38" W

Red Flags: 
Recent loading by new snow, wind, or rain

Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Large and fragile cornices that formed during the storms last week still loomed over wind-loaded slopes. Ski kicks well away from the edge of test slopes with smaller cornices above them caused the cornices to fail and drop onto the slopes below. These cornice pieces did not trigger wind slab failures on the test slopes, but based on the snow-covered debris at the bottom of the test slopes, it looked like those test slopes had already failed during the storm. Ski kicks on wind-loaded test slopes near either end of Wildflower ridge where no evidence of previous failures existed did cause some shooting cracks in the lingering wind slabs. Along the Judah Ridgeline, several natural cornice collapses had occurred recently. Minor evidence of NE winds existed, but I did not find any evidence of significant wind slab formation on W-SW aspects. 

On the shady N facing slopes, the snow stayed soft and cold all day long. A snowpit on one of these sheltered N aspects did contain the buried surface hoar layer about 50cm from the surface, but it had already collapsed and was starting to round. Snowpit tests did not yield unstable results on this or any other layers (see snowpit).

Warm temperatures and sunny skies created wet sticky snow on sun-exposed slopes by noon. 

Photo 1: Skier triggered cracks on an E to NE facing wind-loaded test slope.

Photo 2: Ski kick caused cornice failure several ft. away from the edge of the cornice above a wind-loaded test slope.

Photo 3: Collapsed and rounding buried surface hoar.

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
Air temperature: 
Above Freezing
Wind Speed: 
Air temperature trend: 
More detailed information about the weather: 

Warming temperatures, calm wind, and sunny skies today.