Observation: West Bowl 1/8/2012

Observer Name:

Primomo/Robbins

Region:

West Bowl
Silver Fork
Big Cottonwood Canyon
Salt Lake

Observation Date:

01/08/2012

Location or Route:

Westbowl of Silverfork

Weather

Sky:

Overcast

Wind Direction:

North

Wind Speed:

Moderate

Weather Comments:

Mostly cloudy, winds from the North seemed strongest around noon. -8C just below 10,000ft. at 2:30pm. Air temperatures seemed to drop quickly in the afternoon.

Snow Characteristics

New Snow Depth:

New Snow Density:

Low

Snow Surface Conditions:

Powder

Faceted Loose

Wind Crust

Snow Characteristic Comments:

Light to moderate drifting onto the Southerly aspects was occurring throughout the day, creating an interesting double cornice on the divider ridge of Emmas. No slab buildup was observed within the new snow, except for right off of the ridgetops, and the new snow seemed to be bonding well to the old suncrust. Many North and East aspects have been stripped of their new snow down to the dirty old slab.

Red Flags

Collapsing

Red Flag Comments:

A few good collapses (whumphs!) were heard and seen in the same zone: on an E aspect in Westbowl at 9600ft. The largest was a good 35ft. diameter, and all failed on large grained basal facets well below the raincrust, just below the 12/21 storm layer. Interesting thing about this was that it failed while on a skin track that we had previously laid down an hour earlier. The dusty slab was about 6 inches thick here. We played the angles game well, but had it been steeper...

Primary Concern

Primary Concern:

Persistent Slabs

Probability:

Considerable

Aspect:

North

Northeast

East

Elevation:

High

Mid

Trend:

Same

Primary Concern Comments:

Advanced basal facets, mmm, so tasty, yet so tricky. They are "strong" in compression, but weak in shear... In the words of a good friend; Our snowpack is "uglier than your redheaded stepsister" (no offense to redheads or stepsisters).

snow_profile_location:

Comments - Photos - Videos (group 1)

Decomposing rain crust, just a millimeter thick, turning to striated cups and some chains. No collapsing on this layer but found the cups really cool to see growing with the ice crust.

Comments - Photos - Videos (group 2)

This ones for you, Kobernik. Photo of a facet chain in which a collapse was felt and seen, proof of advanced faceting. It is shown on a 2mm grid.

FORECASTER NOTE: Nice work Matt!! This is strong stuff. I really like your method of backing the facets below the crust with your card to give them contrast. Pulling out the facet chain without busting it up is a good trick also. Well done, your hired.

I also have experienced a previous skin track collapse. It was a skin track that was broken the previous day. No less then 10 people had walked on it. It collapsed when my party walked on it the next day. Not only that but it collapsed in the EXACT same spot on THE NEXT LAP!! Wild.

Furthermore, redheads are good to go in my book.

Kobernik

Observed Danger Rating:

Considerable

Forecast Danger Rating:

Considerable