Johnson Canyon observation tour

Location Name: Johnson Canyon Region: Donner Summit Area Observation Date & Time: Friday, February 24, 2023 - 12:00
Location: 39.333080, -120.288330 See map: CalTopo	Is this an Avalanche Observation?: No Conditions Alerts: Other Signs of Instability (cracking, whumpfing, collapsing) Recent Loading Recent Loading›Blowing Snow Recent Loading›More Than a Foot of New Snow Recent Loading›Snowfall Rates of More Than 1 in/hr

Observation made by: Guide at Blackbird Mountain Guides

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Observation

Description of Snow, Weather, and Avalanche Conditions:

Observations from a morning tour at Johnson Canyon:

In sheltered areas the HST (from2/21 afternoon to present) varied from 55 cm to 65 cm
Moderate SE wind at 7400'
30-minute measured snow fall rate S2@10:30 AM
In areas with less than 30 cm new snow skis penetrated easily to the 2/21 surface crust, new snow wasn't bonded well to the cust layer, dust-on-crust skinning in those areas
In areas with more than 30 cm new snow and at steeper sections of the skin track the snow fractures into slabs with cracks propagating a few meters from skis

I-80 westbound empty at midday

$Along steep sections of the skin track deep snow was fracturing in front of skis$

Along steep sections of the skin track deep snow was fracturing in front of skis

$Along steep sections of the skin track deep snow was fracturing in front of skis$

Along steep sections of the skin track deep snow was fracturing in front of skis

In shallower areas <30cm skis penetrated to the 2/20 surface crust

Weather Details

Elevation of Observation:

6000-7000 ft.

7000 - 8000 ft.

Blowing Snow:

Light

Wind Direction:

Southeast

Wind Speed:

Moderate

Sky Cover:

Overcast - Cloudy - 8/8 covered

Highest Precipitation Rate:

Moderate Snowfall (S2 = 2 cm /~1 in per hour)

Precipitation:

Snow

Air temperature:

Below Freezing

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Johnson Canyon observation tour

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Johnson Canyon observation tour

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