Seattle Ridge

We rode into the back bowls of Seattle Ridge and spent the most time on the south end of the drainage near the headwall. We saw one very large recent avalanche that looked to be triggered by a snowmachine in the past two days. 

We saw a very wide propagating avalanche in an upper bowl just north of the headwall off Seattle Ridge (location is the pin in this report). This slab appeard to be snowmachiner triggered sometime in the past two days. It was 1-2' deep and possibly as wide was 1,500'. Debris ran over several snowmachines tracks in a gully feature below. See photos. According to a group we ran into later, the debris was up to 15' deep. It is likely the weak layer was the Valentine's Day buried surface hoar. We also had a report of two smaller snowmachine triggered slabs ( one near the Seattle Headwall and one near Triangle Bowl) that occurred today.

We dug in two places today in Triangle Bowl. The first pit was 50' or so off the ridge and we did not find any weak layer (around 3,000' west aspect).
Our second pit was lower down the slope (500' feet or so below the ridge at 2,500' west aspect). The weak layer was around 14" deep and very stubborn and did not propagate (ECTN 26, PST 65/100 end). In our PST test the weak layer was hard to get to fail but once it did it poped right out. 

These pit results suggest it's getting harder to trigger a big and scary avalanche but still possible. A tricky situation.