Trees East of TJ

SNOWPACK OBSERVATION
Between Hammil and TJ
Submission Info
Forecaster
Monday, April 16, 2018 - 12:00pm
Red Flags: 
Recent loading by new snow, wind, or rain
37° 34' 49.44" N, 119° 0' 11.52" W
Snowpit Observations
More detailed information about the snowpack: 

Toured up to 10,200' at the top of the trees that separate the E face of Hammil from TJ Bowl, back down the same way. Terrain observed: below treeline, near treeline. Aspects observed: NE-N-NW-W-SW. Light to moderate snowfall throughout the day with 15cm new snow at 9000' at 10am and 25cm new snow at 10,000' at 11am. Plenty of light to moderate blowing snow, generally from WSW winds.

Test slopes primarily had very small to D1 sluffing results. Some wind loaded test slopes had short cracking and cornice drops triggered sluffs on slopes below. Results from kick tests and ski cuts were touchy - easy to skier trigger - on E-N-W-SW aspects between 9000' and 10,200' near and below treeline. Loose dry results were more touchy than wind drifts which were relatively soft: F+, but up to 45cm thick in isolated areas down wind of crossloaded ridges. My largest ski cut result was a D1 loose dry avalanche that I triggered on a 40 degree N facing slope at 10,100'. The snow failed within the top 5cm and entrained the full 25cm of the new storm snow by the time it came to a stop about 40' down the hill where the slope angle lessened. The slide was 30' wide. The bed surface was a 1F hard melt-freeze crust. See videos and pictures of test slopes. No natrual avalanches observed on the Crest - poor visibility.

The new snow was poorly bonded to the melt-freeze surface from Saturday-Sunday. At 9000' the melt-freeze layer was P+ hard, dry and frozen, and 20cm thick with 1F hard moist melt forms underneath. Above about 10,000' there was a F hard 5cm thick faceting graupel layer that was deposited early during the last quick storm on the night of the 11th. Above that graupel layer there was a 5cm thick 1F hard faceting melt-freeze crust that is the results of the warm weekend temps melting down the storm snow from the 11th. I had several CTVs in the graupel layer but several ECTs did not propagate. In my ski tests I occasionally broke through the upper crust layer but it didn't slide, only the new snow was moving.

Snowpack photos: 
D1 loose dry ski cut results, N facing slope 10,100'
Small sluffing, W facing slope
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Moderate to strong winds observed at all elevations today with associated light to moderate blowing snow. Winds generally from the WSW, but local channeling created variable wind directions depending on location. Snowfall consisted of a mix of irregular snow crystals and graupel. Snowfall rate throughout the day was light to moderate with a period of very light to no snowfall around 1230-100pm. The top 5cm of the new snow was showing some signs of settlement with minor cracking, but was still F hard like the rest of the new snow. Sky was obscured by moderate snowfall and strong winds for much of the morning with periods of broken clouds around noon. Temps stayed cold, -6deg C at 10,000' at 1130am. Weather moved back in with precip again picking up in the later afternoon.

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