Windslabs and Whumphing in Virginia Lakes

Submission Info
Thursday, December 21, 2017 - 3:45pm
Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
38° 2' 38.7708" N, 119° 14' 40.4736" W
Snowpit Observations
More detailed information about the snowpack: 

Toured today out of Virginia Lakes, skiing the glades off South Peak and Mount Olson. Did not go to the summit of either due to extreme wind scouring. 

Surface quality was a mix of icy sastrugi-like snow, hollow sounding windboard (5-10cm thick) and dense DFs. Snow unafftected by the wind down in the trees was quite good. Average depth of new snow was 15cm but on lee slopes was up to 30cm

Skinning from South Peak to Olson saw a change in the thickness of the old windslab (new snow was not showing slab characteristics), up to 25cm. On a NE aspect, 10200', 25 degree slope, had two separate slope-scale whumphing events. Dug handshears in these locations and found a 25cm thick P+ slab sitting on 15cm of large grained facets, failing with moderate force. Did not do any standard tests, did not see shooting cracks longer than ~1m and had no kickturn test results.

Weather Observations
Blowing Snow: 
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: 
More detailed information about the weather: 

Less windy than forecast had indicated, winds far below threshold for windslab formation, but plenty of loose snow on the ground to move when the winds pick up again.

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