Storm and wind slabs in June backcountry

SNOWPACK OBSERVATION
Ghost Trees
Submission Info
Member
Friday, March 19, 2021 - 5:00am
Ghost Trees 37° 44' 40.3368" N, 119° 6' 9.7092" W
Snowpit Observations
More detailed information about the snowpack: 

We toured into the June backcountry today to see how new snow was bonding and look for wind slab formation.    During the tour we saw no recent avalanche activity and no whumpfing. 

 

 At 9 AM., the air temp was 37°at 7600ft and very wet snow was falling.  Accumulations of 8-10cm were seen near Yost meadow (9100, ft).  Higher in the Ghost Trees, accumulations of 10-12 cm were seen.  Snow was dense and spongy.  Strong ridge top winds  were moving snow around all morning.  Wind direction was variable throughout the day, primarily from the north and west though.   Along exposed ridges, I was able to get many small, loaded convexites. to crack under foot.  These fractured on the new snow/ old snow interface and did not propagate.

 

Touring in the Ghost Trees, ski pen was up to 25 cm in sheltered areas.  Boot pen calf deep.   We found hand pits to fracture with moderate force at 30 cm depth. These clean, planar fractures failed at the interface of the old melt freeze crust and last week's new snow; failing on a density change from 4 finger new snow to 1 finger old snow.  We had minor cracking at the new snow/old snow interface in sheltered areas (see photo).  These cracks only occured under foot and did not propagate.  Ascending higher, these small, 4 inch deep soft slabs occured at nearly every kick turn but never propagated. Closer to the ridgeline, small convexities showed more of a wind slab character.  These failed with stomp tests, breaking into 4 inch deep slabs.  While we felt reasonably safe with these conditons on treed slopes, I would imagine that above treeline could be a different story. 

 

The only avalanche activity we saw was a small slide that we were able to initiate on a steep, convex roll (see photo).  This 4 inch deep slab was no more than 20 ft wide and ran 150 ft.  It slid on the new/old interface. 

 

Winds were moderate to strong during the day and our skin track was mostly filled in by the time we started our second lap. 

 

Surface conditions were enjoyable down to 8500 ft, where the snow became noticably more wet and slushy.  Slow speed water skiing on the run out from Devil's Slide. 

Snowpack photos: 
Small storm slab initiated on a steep convexity
Shallow cracking under foot during kick turns
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Northeast
Accumulation rate: 
Less than 1 in. per hour
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