Details

• Date: 2023/01/14

• Observer: Chris Bilbrey
• Organization: Forecaster, CAIC

Location

• BC Zone: Southern San Juan
• Area Description: Central La Plata Mountains

Weather

• Ridgeline Wind Speed: 5-10 mph
• Ridgeline Wind Direction: S
• Wind Loading: None
• Sky Cover: Overcast
• Weather Description: Mild, overcast day with a light south wind along ridgetops.

Snowpack

• Snowpack Description: We traveled across various aspects to evaluate surface conditions in advance of a prolonged stormy period. We found a widespread crust on east-facing slopes continuing along the southern half of the compass that ranged from around an inch thick below treeline, and tapered to around half an inch near the treeline. The crust was more robust and supportive below about 11,000 feet becoming breakable as we climbed higher. Directly below is a softer (4F) layer of decomposing grains and near-surface facets still dry despite recent surface wetting from above-freezing temperatures. Digging on a south-southwest aspect at 11,600 feet, we identified two layers of concern in the top 40 cm that produced sudden collapse failures with easy-moderate force. Around 60 cm, we found another layer, but this one was more reluctant to fail and needed an extra couple of taps to produce a resistant planar failure. The rain/ temperature crust during the holiday storm was around 70 cm below the surface in our southerly snowpit with tiny facets below. This layer was unreactive in tests. Probing across northerly aspects, soft F to 4F snow sits on the surface, and we could feel softer layers below that are likely storm/ density changes during the holiday storm. These were mostly in the top 60 to 80 cm range with the stout main slab body below. Once we broke through the main slab, weaker, collapsible snow layers lurk below but likely need a major load to provoke natural failures near the ground. Poking at a couple of old crowns on north-facing slopes, we found about 60 cm of snow above the old bed surface which was a mixture of faceted grains near treeline to a knife-hard layer below treeline. Slopes that avalanched back in December seem possible to fail again, especially once a dense storm slab layer is added above. While exiting the mountains midday, the snow surface on all aspects below 10,000 feet, except due north, was starting to get damp and sticky.

Avalanches

• Avalanche Description: Extensive roller ball activity and small point release sluffing on east through south to west-facing slopes from yesterday's sun and warm temperatures - especially above the treeline. Numerous old, large slides on north-facing slopes below treeline in old-growth timber, likely running during the New Year's storm. These slides deposited impressive snow piles at the bottom of slopes and in gullied terrain features. The last time this treed slope ran this big was during the 18-19 winter.

	Date	Location/Path	#	Elev	Asp	Type	Trig	SizeR	SizeD
	2023/01/02  †		1	<TL	NE	SS	N	R1	D2
Date: 2023/01/02 (Estimated) Observer: Chris Bilbrey Organization: Forecaster, CAIC Area Description: Bedrock Creek Elevation: 10800 ft Sliding Surface: O - Within Old Snow Weak Layer Grain Type: Faceted Crystals
	2023/01/02  †		4	<TL	NE	SS	N	R2	D2
Date: 2023/01/02 (Estimated) Observer: Chris Bilbrey Organization: Forecaster, CAIC Area Description: Ridgeline between Boren and Bedrock Creeks Sliding Surface: O - Within Old Snow Weak Layer Grain Type: Faceted Crystals Average Crown: 24 in Maximum Crown: 36 in Comments: Slides ranged from about 10,600 feet up to 11,400 feet.

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