Avalanche: Pebble Creek Backcountry

Observer Name
Keith Reinhardt
Observation Date
Friday, January 10, 2014
Occurrence Date
Friday, January 10, 2014

Region:

Location Name or Route
Pebble Creek Backcountry, via Bomb trail
Comments

Here's a report from my friends who hiked up to the backside this a.m.  They dug a put just south of the Lama/northside of the saddle (accessed by the bomb trail).  As you can see below, they had column and extended column failure at CT=1.

 

Just one aspect (N-NE), and just one pit, but I thought you should know about it, and let hikers know about it as you see them.

 

Coming back down the front side, they noted that the avalanche-prone area above Stacy's had slid, but presumably this was due to control work?

 

See you tomorrow.

 

Keith

 

 

REPORT:

This morning 01.10.13 we hiked up to the backside via the bomb trail. There was good coverage most of the way but also an unfortunate tortilla-like, easily breakable sliver of ice on the ungroomed snow surface. The groomers were icy too. The only stellar snow was in the trees fairly high on the frontside slope (above 8000 ft.). Once over the top we descended 50-100 feet and on a Northern to NE aspect which was 25 degrees approximately we dug a pit. There is a very reactive layer right now about 8in. in depth. The column tests failed early, quickly, and in a alarming planar manner. With snow and especially wind set to arrive later today/tomorrow, please be careful out there. I wouldn't be surprised to hear of slides occurring. We saw Ryan Butterfield on our descent so maybe someone should check in on him. He was alone. Here are the stats:

General observations: 

The snow pack was 85 cm were we dug. We were just south/sw of the llama. The slope was about 25 degrees facing NE. The wind was blowing from the south/sw at a good clip. I didn't have a gage but the weather reports says 25 mph. There were several faceted layers: The first was about 8cm from the surface and the second was near the bed surface approximately 55 cm in depth.
 

Column test:

CT1 Q1 The strength of the identified layer (about 8cm deep) was super weak. The column collapsed very easily (immediately) on a faceted layer..maybe buried surface hoar. When I continued the column test the next failure occurred at CT12. We did not determine the quality of the shear as it occurred on the ground

 

Extended column test:
ECT1 Q1. Alarming failure. Reactive. Fracture extend 60cm laterally (i.e., the whole column--see image attached). This was the same layer as discussed above.  When I continued the test, no further failures were noted

Coordinates