Date of Observation: 02/02/2021
Name: Zach Guy
Zone: Northwest Mountains
Location: East Beckwith
Aspect: North East
Elevation: 9900-11500′
Avalanches: Noteworthy cycle of persistent slabs on the west side of the Ruby Range (W and SW aspects N/ATL). See photos. Many of these likely ran on Sunday triggered by wet loose slides or simply warming. The others ran mid storm on Saturday. These slides are important because they are the first persistent slab avalanches we’ve observed on these windward aspects since the new year.
In our travels today, the only steep slope we approached collapsed, cracked wall to wall, but didn’t slide. Small, unsupported rollovers were easy to trigger, soft slabs breaking on 1/19 interface, 18″ deep or so.
Weather: Creepy warm. Noticeably warmer on the west side of Kebler Pass. Mostly cloudy skies until clearing late afternoon.
Snowpack: Widespread collapsing below treeline, with some shooting cracks and collapses radiating over 200 feet across slopes. Emerging to near treeline, slabs are thicker and more stubborn. We didn’t get signs of instability underfoot near treeline, but tests produced consistent moderate propagating results down 2 to 3 feet under 1F slabs.
Snow surfaces were moist to 10,400′ on northerly aspects. Below treeline, the super soft slabs of earlier this week are now stiffer and capable of propagating further, thanks to settlement the last few days.
Snow surfaces going into the storm on north-facing terrain: Fist hard DF’s near and above treeline, not an alarming layer. Below treeline, and somewhat unique to our snowpack climate, we saw melt-layer recrystallization occurring at the end of the day (see photo), the result of warm, cloudy conditions melting the snow surface this afternoon and then abruptly changing to clear skies with good radiative cooling on the surface. Dry, small-grained facets over a soft meltfreeze crust exist below 10,400′ on the surface of shady aspects here. There were also isolated areas of surface hoar that got cooked off by the end of the day below treeline.
Photos:
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- Unstable result 3 feet deep, NE NTL
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- Unstable result, NE BTL
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- Shooting crack spanning the entire slope
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- Natural that ran Saturday, NE BTL
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- Easy to pop persistent slabs on unsupported features.
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- D2s below Ruby, SW aspects NTL. Likely ran 1/31
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- D1.5 and D2s below Ruby, SW aspects NTL. Likely ran 1/31
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- D2 below Richmond. SW ATL. Likely ran 1/30
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- D1s wet loose and slabs, SW NTL below Owen. Likely ran 1/31
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- D2 PS slabs on W/SW bowl below Owen. Likely ran 1/30 and 1/31
