Negatives & Hemlock - lots of wind effect, no signs of instability

Negatives & Hemlock
Submission Info
Friday, February 22, 2019 - 1:15pm
Red Flags: 
37° 43' 48.27" N, 119° 5' 59.2728" W
Snowpit Observations
More detailed information about the snowpack: 

Toured off of June, up hourglass, down Negative 1, up Hemlock ridge and down 4 seasons to rd.  Beautiful sunny day, no clouds, and NO WIND! ...Except for just after sunrise driving by Mt. Morrison above convict, NE winds were blowing snow off the summit there, but no wind visible anywhere around the mtns sourounding June.  6-8" of very low density fluff at the surface of the snowpack in protected areas.  

Lots of widespread wind effect in negatives, lots of firm windboard with areas of nice soft snow in lower half.  Atleast 6 new tracks throughout negatives today, no evidence of unstable windslab, small or large.  See attached photo of raised skin track going up basin above hourglass couloir.  

Dug a test pit on approach on SE aspect in area of most concerning wind deposit I could find where handshears failed cleanly with moderate force.  ECT tests however did not popogate.  22cm of 4F- wind deposit ontop of 12cm of P+ firm older wind deposit ontop of 10cm of 1F+ ontop of 4F+ snow to bottom of pit (only 50cm deep pit).  Tests failed at bottom of upper-most layer (CT11Q2 22cm down, ECTN22 22cm down times two.) and at the top of the bottom-most layer (ECTN23, CT23Q2).  Not very concerning results.  

Biggest concern found in Negatives was potential for a long slide if someone fell.

Hemlock Ridge was much more protected, and still offered quite good powder skiing in the central more protected trees.  On either side near ridges, lots of wind stripping evident, and challenging skinning conditions on firm windboard.  Good amount of sloughing still occuring in steeper sections.  No signs of sensitive slab though anywhere.

Lower elevation slopes of 4 seasons also held protected soft snow, but below 8400' rain crust could be felt easily thru the thinner overlying snow.  Dug a pit at 8575' to investigate the rain crust, see attached profile.  No signs of faceting above or below it, and low temperature gradient sourounding crust at this point isn't condusive to faceting (Rain crust actually is -5°C).  Stability tests showed no signs of weakness sourounding the crust.  A thin dense layer near the surface however did fail easily with column tests, but ECT tests did not propogate.  Also of note, this firm layer was discontinous even within a meter of the center of the pit.     

Also of note, no wet loose activity seen on any solar facing slopes with this first full day of sunshine.   


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

Cold day still, between -5 and -10°C between 8500' and 11,000' for majority of day.  

-- placeholder --

ESAC receives significant financial support from ...