Persistent weak layer

Yost Meadow Trees
Submission Info
Volunteer Observer
Saturday, January 12, 2019 - 7:00pm
Yost Mdw. Trees 37° 43' 39.9576" N, 119° 5' 28.2084" W
Snowpit Observations
More detailed information about the snowpack: 

Toured from the top of June Mountain to Yost Mdw. Enjoyed good skiing in 10- 15 cm of loose dry snow. We saw a lot of surface hoar on all aspects in open areas and open tree glades. Up to 3mm in size. Yost Mdw. ski pen 10 cm, boot pen 45 cm. Then we climbed up in the Yost Mdw. trees to above 10'000ft. Mostly loose dry snow ( 10- 15 cm) with SH in open areas. All aspects in sheltered trees are holding nice loose dry snow. Did not see wind transport but any time we travelled in more exposed places such as near shoulders or rollovers, there was evidence of previous windloading. The wind slab broke under our skis and cracks shot out a short distance ahead. Windslab 2- 15 cm thick. Looking up into the Negatives and across at White WIng there is obvious wind effect on the snow in any open or exposed areas. 

I looked for the persistent weak layer in several places and found it. At 9645 ft in a NE aspect climbing up into the Yost trees, S of the meadow: 20 cm of loose dry snow, then 50 cm of 4 F to 1 F slab over 30 cm of faceted, sugary snow. Dug a pit up higher and found the facets again, but deeper down. See pit profile. 

Skied up into Dream Bowl and looked for the PWL. Found it on NNE aspect at 9920 ft. 75 cm dow. 1.5 mm facets below a 50-55 cm slab 4F to 1 F slab and 20 cm of loose dry snow at the surface. 

Besides the SH we also observed near surface faceting in the top cm's of the loose dry snow. 


Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Air temperature trend: 

ESAC receives significant financial support from ...