Wednesday, December 17, 2008

Avy Report -- December 17, 2008

Avalanches in the News:

December 14, 3008 -- Man Killed in Aspen Avalanche
December 14, 2008 -- Woman Killed in Snowbird Avalanche
December 7, 2008 -- Police Launch Appeal After Series of Fatalities
December 7, 2008 -- Book Honors Avalanche Victim

The Avalanches in the News information was obtained from the AIARE website.

Northwest Avalanche Profile:

The following is raw information obtained during an AAI Avalanche Course. We are posting this on a weekly basis so that trends may be followed by those that are interested.

Region: North Cascades
Date: 2008/12/13-14
Location: Mount Baker Ski Area
Activity: AAI’s AIARE Level I Avalanche Course


Students used Skis, Snowboards and Snowshoes for flotation.

We found a snowpack of 90cm to 110cm (3-4 ft) found 30cm to 35cm of new snow sitting on top of a 1.5 cm thick pencil-knife hard rain crust. This seemed consistent throughout the Ski Area.

On N to NNW facing slopes with a 28-29 degree incline, all of the compression tests caused failure on top of this crust, under the new snow layer. This varried from CT13 to CT16 Moderate Scores at elevation between 4200 to 5200 ft. On a 29 degree slope a Rutschblock Test score RB5 with Q3 quality shear EB Release Type (Edge of Block = 10-40 %).

At 4300 ft and at 5200 ft on a 38 degree slope, we obtained a score of RB4 with a Q2 quality shear failure. This was characterized by a MB Release Type (Most of the Block = 50-80 %) at Artist point area.

There was plenty of new light-weight snow available for wind transport. This was clearly visible throughout the day with snow being transported to the top of south facing slopes on both Saturday and Sunday.

On steeper terrain (about 40-45 degrees) we observed two loose snow releases. We observed them on the NNE shaded slopes below the Table Mountain Chimney area. Both of the releases were probably due to the fact that they were located in shallow convex/concave terrain.

In places the snow seemed scoured to the rock from much of the snow cover due to wind and the poor anchoring. Temperatures were -14C or about 9F to 10F at midday Sunday the 14th.

--Richard Riquelme

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