Strong Winds and Reactive Windslabs Near June Lake

SNOWPACK OBSERVATION
San Joaquin, Negatives
Submission Info
Forecaster
Wednesday, January 1, 2020 - 12:15pm
Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Snowpit Observations
More detailed information about the snowpack: 

It was a warm and windy day in the June Lake backcountry today.  I toured from the top of J-7 via the ridge separating Glass creek and Yost creek with the goal of topping out on San Joaquin and descending via the Negatives.  Moderate to Strong NW winds were present throughout the day at all observed elevations and significant transport was occurring near and above treeline. On my route out to the Hourglass, I found many areas of recent deposit along the ridgeline. Poking around on some leeward catchment zones I observed recent cornice growth, shooting cracks up to 5 ft in length and I was able to kick loose several small avalanches. (D1 at most) Wind speeds at this location were ideal for deposition, and crown heights were 12-18” in depth. A quick pit adjacent to one of the larger slides showed the recent slabs to be 1F/F, and sensitive. (Hand sheers and compression tests both failed on isolation) I also noted that surface snow was damp, and the blowing snow had a rime like feel to it. I suspect the relatively warm air temp and the solar input was leading to this trend. 

Looking up at the Negatives, significant flagging was occurring by 10 am this morning, and recent tracks were largely filled in.  I was briefly sheltered from these winds as I made my way up through the Hourglass, but as I reached the top of the Negatives, wind speeds had increased substantially. Gusts were strong enough to challenge my balance, and the blowing snow made for an uncomfortable place to transition.  Continued wind loading kept me from dropping into the negatives today. I opted instead to descend back down the hourglass. Descending from the shoulder of San Joaquin surface conditions were variable. Supportable wind board, and some textured softer snow made for a better than expected decent above the choke of the hourglass, and below the surface conditions were quite enjoyable. 

Skinning back to the base of J-7 from the base of the negatives, I noticed that surface snow on more solar aspects had warmed up quite a bit. Some minor roller balls were observed below rock outcroppings near 3D chute, and surface snow was collecting into softball+ sized weights on the tips of my ski poles.

Snowpack photos: 
Snowpit videos (tests, etc): 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Strong
Precipitation: 
Air temperature trend: 
Warming
Wind Direction: 
Northwest
Accumulation rate: 
More detailed information about the weather: 

Warm temperatures and mostly clear skies persisted throught the day accompanied by strong to gale-force winds.

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