Details

• Date: 2019/12/24

• Observer: Ryan Lewthwaite
• Organization: Forecaster, CAIC

Location

• BC Zone: Front Range
• Area Description: St. Mary's Glacier

Weather

• Ridgeline Wind Speed: 5-10 mph
• Ridgeline Wind Direction: SW
• Wind Loading: Previous
• Temperature: 1.2 C
• Sky Cover: Few
• Depth of Total Snow: 123 cm
• Weather Description: A warm day with mostly clear skies & 34 Farhenheit. The winds were calm to light out of the southwest. No snow was available for transport, but there was evidence of previous wind loading.

Snowpack

• Snowpack Description: Most of the unprotected snow was wind scoured in the near and above treeline areas. The firm wind-packed surface snow was impenetrable by skis or boots. Very little snow lingers in the above treeline area, and what does exist is isolated to leeward terrain features. I dug in a snow drift above treeline at 11,700' and found firm snow over-top of loose facetted snow. Above St. Mary's Lake (x3) R2D2 avalanches had released with the new snow accumulations almost a week ago. One of the avalanches deposited debris onto the hiking trail. I dug a snowpit on a similar east aspect and adjacent to the slides, please refer to Snowpilot. A notable rain crust was knife hard and riddled with pine needles and cones, likely associated with a strong wind event. The facets above this crust was my primarly layer of concern, causing failures in stability tests with moderate force.

Avalanches

• Avalanche Description: Just above St. Mary's Lake on a steep east facing slope, three avalanches had released with the new snow that accumulated almost a week ago. It likely was a single avalanche that caused the three paths to run all of which terminated on the lake ice. The northern most avalanche deposited debris on the very popular hiking trail. Crowns were distinct and had depths ranging from <12" to >24". The bed surface was an older layer of wind-packed snow roughly 95cm deep.

	Date	Location/Path	#	Elev	Asp	Type	Trig	SizeR	SizeD
	2019/12/18  †	Other	1	TL	E	HS	N / U	R2	D2
Date: 2019/12/18 (Estimated) Observer: Ryan Lewthwaite Organization: Forecaster, CAIC Area Description: Directly above St. Mary's Lake to the west. Landmark: Other Average Slope Angle: 44 ° Maximum Slope Angle: 50 ° Elevation: 10900 ft Sliding Surface: I - New/Old Interface Weak Layer: Layer Weak Layer Grain Type: Decomposing or Fragmented Average Crown: 16 in Maximum Crown: 26 in Average Width: 80 ft Maximum Width: 100 ft Average Vertical: 300 ft Maximum Vertical: 400 ft Comments: Many novice hikers in the area and under avalanche terrain.

Media

Images