South Peak - Virginia Lakes

Please help!  Post your observations to our site under the "Participate" Tab... Click Here to Find Out How

SNOWPACK OBSERVATION
South Peak
Submission Info
Forecaster
Thursday, April 12, 2018 - 11:45am
Red Flags: 
Recent loading by new snow, wind, or rain
38° 2' 22.56" N, 119° 15' 18.72" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up to within 200' of the top of South Peak from the Virginia Lakes winter trailhead to see wind slabs. Aspects observed: N-E-S. Elevations observed: 9700'-11,200'.

Snow amounts around the Virginia Lakes was no more than 5" last night (VGR weather sensor) with likely more higher up towards Frog Pass. There was little in the way of just undisturbed storm snow sitting on the ground, it seemed to all have been blowing into new wind slabs and drifts from W winds onto NE-E-SE-S aspects from the trailhead to the top of the peak. New slabs and drifts were generally small and specific to the lee of treed areas and gullies. Almost all surfaces were 1F+ to P to K hard rimed melt-freeze crusts. The snow under the crust has faceted a little with the sudden drop in temps but there are still frozen polycrystals mixed in down about 30cm to another very hard crust. Wouldn't have gotten as high as I did without ski crampons, boot crampons would've been a good idea for getting to the top, but why ski another 200' of bullet-proof crust? Many hand shears on the way up pulled partial or whole block with moderate to hard force within the F- hard DFs under the F+ wind deposits. Wind slabs observed were generally soft, shallow, and small with a few being more than 15cm thick and larger than 40'x40'. Stomped on new drifts on the S side of the saddle between South Peak and Mt. Olsen on the way up with no results. Snow that had drifted onto that S aspect at 10,700' and above was cold dry wintry snow. No coverage on S aspects beneath the drifts just leeward of the ridge. Once I decided that slabs were soft, shallow, not doing much, and expected results to be small I also ski cut the loaded sidewalls (skier's L) of the NE and N gullies with very small and isolated plating and cracking but nothing sliding. Skiing was dust on crust. Found a more loaded feature near the bottom of the N chute at 9925' on a NNE aspect where the drift was 35cm deep and I had my only real ski cut results of the day. See photos of all ski tests.

No visible natural or skier triggered slides in the drainage while I was there. S aspects down low seemed to be warming on my way out. No new point releases or rollers from the S gully of Dunderberg yet.

Snowpack photos: 
Small ski cut results in a 35cm deep wind slab
Small ski cut results in a 35cm deep wind slab
Small ski cut results in a 15cm thick wind slab
Small cracking on a test slope
Periods of light blowing snow off of the NE ridge on South Peak
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
West
Accumulation rate: 
None
More detailed information about the weather: 

Brisk for spring: Tair at 11200' at noon= -9.5deg C. Sky=Few clouds, Winds generally Light from the W. Light and specific areas of blowing snow across the tops of peaks from W-NW winds in the drainage. On the way up there was more widespread light to moderate blowing snow from Mt. Wood N to Dunderberg. On the way home I couldn't see any more blowing snow across the Sierra.
 

ESAC receives support from ...