Details

• Date: 2011/02/21

• Observer: Public

Location

• BC Zone: Front Range
• Area Description: In RMNP Monday
• Route Description: Short tour from Bear Lake to Dream Lake and back.

Weather

• Weather Description: Partly cloudy, strong W winds, Intense blowing snow; H -10c.

Snowpack

• Snowpack Description: Very reactive windslabs on N and E aspects well below treeline. 2 avalanches observed-- I triggered one on a test slope (150 m WNW of Nymph Lake, el. 9880') I use most weeks (about the largest it's run). E aspect, 35-38 degrees, AS, SS, crown depth 35-50 cm, 30 m across, D1.5, ran on NS facets at the new snow/old snow interface; triggered remotely (about 4 m below me) before I even moved out on the slope.
  
  Another small avalanche was triggered by 3 skiers on a NNE aspect in the Dream Chutes just S of Dream Lake (el. 10,200')-- in steeper (40+) terrain, similar 50cm crown, fracture line almost 60m across-- this triggered on a convex wind roll in a cross loaded gulley, no one was caught or injured.
  
  Also plenty of shooting cracks when crossing wind rolls-- the slabs are stiffening and have significant energy for propagation.Variable, 10-50 cm of new snow, mostly wind deposited, over the old snow surface. Hard crust on old snow surface on sunny aspects, variable stiffness of old snow layer on shadier aspects.

Snowpack Obsvervation #1 Cracking: Shooting Collapsing: Minor Persistent Weak Layer: Yes Comments: Quick fracture line profile of test slope above Nymph Lake (largest part of crown): 0-12 cm: F, + 12-20 cm: 1f, dfs 20-50 cm: 4f, dfs 50-51 cm: F, facets-- SS slid on this 51-54 cm: P crust

Avalanches

	Date	Location/Path	#	Elev	Asp	Type	Trig	SizeR	SizeD
	2011/02/21		1	TL	N	SS	AS
Date: 2011/02/21 Average Crown: 50 cm Maximum Width: 60 m
	2011/02/21	Rocky Mountain National Park	1	<TL	E	SS	AS / r	R4	D1
Date: 2011/02/21 Landmark: Rocky Mountain National Park Elevation: 9880 ft Sliding Surface: I - New/Old Interface Average Crown: 35 cm Maximum Crown: 50 cm Average Width: 30 m