TJ Bowl snowpack

SNOWPACK OBSERVATION
Chutes above TJ Bowl
Submission Info
Forecaster
Thursday, December 22, 2016 - 11:30pm
37° 34' 39.396" N, 119° 0' 26.4204" W
Snowpit Observations
More detailed information about the snowpack: 

-Toured up Lake Mary ridge above Lake Mary and up chutes above TJ Bowl to crest, back down same way

-Tons of crown still visible from Dec 16th storm event, mostly 1.5-2.5ft.  Looks like most steep slopes between 10,200' and 11,000' either slide or sloughed significantly at some point during storm.  Checked out several of these spots where crowns were still visible.  See attached profile which was done at 10,900', N facing slope just above one of these crowns.  Seems that most of the visible crowns were from avalanches that failed in facet layer above 2nd ice crust from bottom which developed during the second major storm/rain event in late October.  Interestingly in this location above this old crown, only 10cm of new snow was above upper thin rain crust which developed during Dec 9th storm event (which ended warm, leading to rain above 11,000').  This means that most likely the slope above had small avalanche(s) that ran ontop of this Dec 9th raincrust, and then stepped down at this point to the deeper old facet layer. (there were no crown remnants above, they were blown in by wind).  

-Another crown checked out slightly lower down at 10,700', WNW facing slope, on the edge of the slope near a rockband.  ECT tests performed just above this crown in the pocket of snow between the crown and the above rockband resulted in energetic propogation across column in facet layer just above Dec 9th rain crust as well as deeper down in facet layer above late October rain crust (all-be-it requiring hard force).  ECTP 27 (27cm down), ECTP 29 (60cm down).  Shallow snowpack here on edge of slope ~75-85cm.  See attached pics of the two failure levels.  Of note,  

-Lake Mary Ridge, 9,300', NE facing slope just below ridgeline = ~3ft of total snow depth.  Upper 2/3 is loose faceted snow, lower 1/3 is coarse icy firm basal column.  

-Interpretation:  The significant loading that occured during the Dec 16th storm event caused wide-spread avalanche activity, both within storm snow, at oldsnow/new snow interface, and stepping down to suspect weak facet layer above late October raincrust at elevations between 9,800' and 11,200'.  There are still plenty of areas where this old raincrust / facet combo still exists, but it is highly unlikley that they will be trigerable by humans. (Another heavy storm such as one forecasted for this Friday Night could be enough to trigger some spots that didn't go in last week's storm event).           

 

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
Clear
Air temperature: 
Above Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
South
More detailed information about the weather: 

Clear beautiful day, mostly calm winds, slight light wind out of the South at the ridgetop (11,200').  Began cold early morning, but quickly warmed to 0deg C at 11,200' at noon, and mid 40s at 8000-9000' level.  

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