Observation Date: 01/07/2012

Route/Location:
We toured to the summit of Red Butte on the east side of the Missions. Followed a forest service road up the East ridge, skied a fairly steep tree’d section of the east bowl, regained the ridge, and skied glades back to the road.

Weather:
7/8 cloud cover most of the day, becoming more bluebird towards the late afternoon. Snow flurries all day with a total of around 4cm of accumulation throughout the day.

Wind:
Towards the 7600′ summit, easterly winds were gusting close to 50 mph for a little while, with sustained winds around 20 mph. The approach ridge had already seen significant wind scour and leewardWind erodes snow from the windward (upwind) side of an obstacle and deposits snow on the leeward (downwind) side. Deposited snow looks smooth and rounded. You should always beware of recent deposits of wind drifted snow on steep slopes. deposition from last week’s high winds, and there was little active transport. There were some sizeable cornices developing, but on this route, they didn’t present much of a hazard, as they mainly overhung low angle terrain.

New Snow: 0-3″

Avalanche Activity:
We did not see any signs of recent avalanche activity, although debris towards the bottom of Red Butte’s east bowl suggested that it may have slid earlier in the season (there was no apparent crown).

On a steep section of the approach ridge, I experienced a large collapseWhen the fracture of a lower snow layer causes an upper layer to fall. Also called a whumpf, this is an obvious sign of instability. with a radius of around 10 feet, as indicated by circular cracks around the collapseWhen the fracture of a lower snow layer causes an upper layer to fall. Also called a whumpf, this is an obvious sign of instability. area. This was on a heavily wind scoured ridge, and the collapseWhen the fracture of a lower snow layer causes an upper layer to fall. Also called a whumpf, this is an obvious sign of instability. occurred where around 2in of wind slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers.A cohesive layer of snow formed when wind deposits snow onto leewardWind erodes snow from the windward (upwind) side of an obstacle and deposits snow on the leeward (downwind) side. Deposited snow looks smooth and rounded. You should always beware of recent deposits of wind drifted snow on steep slopes. terrain. Wind slabs are often smooth and rounded and sometimes sound hollow. broke over around a foot of highly faceted, unconsolidated sugar.

We dug a large pit on a 27deg NE slope in fairly open trees, and performed several tests. Total snow depth was 130cm, and temperature at the time was 16 degrees F, and the elevation was around 7400 ft. Snow hardness was similar to other places in the advisory area, with fist hardness in the top 30cm, to 4f for another 20, and then rotten fist hardness facetsAngular snow with poor bonding created from large temperature gradients within the snowpack. the next 80cm to the ground. Total depth was 130cm at around 7400ft. Compression test yielded a CT7Q2 at 10cm depth, with very little energy. It was also in soft snow, not very slablike at all. Continuing the compression test yielded a CT22Q2 at 25cm depth. An extended column compression test yielded ECT24Q3 with no propagationThe spreading of a fractureThe physical separation of the slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. from the bed surface and surrounding snow during the initiation of a slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. avalanche. or crackThe spreading of a fractureThe physical separation of the slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. from the bed surface and surrounding snow during the initiation of a slabA relatively cohesive snowpack layer. A layer of snow stronger than underlying layers. avalanche. or crack within the snowpack. within the snowpack. at the same 25cm layer. Shovel shearing both of these columns after completion of the compression tests yielded an energetic Q2 failure at 110cm, deep within the mass of faceted snowAngular snow with poor bonding created from large temperature gradients within the snowpack..

Based on the pit, and keeping in mind the collapseWhen the fracture of a lower snow layer causes an upper layer to fall. Also called a whumpf, this is an obvious sign of instability. earlier in the tour, we felt comfortable skiing steep tree’d terrain, but opted against committing to big, open terrain.

Other Comments:

Observer: Doug Brinkerhoff