Why did the avalanche cross the road?

Trail ride from Olney along the west side of the Whitefish Range, to take advantage of good visibility and get a sense for natural avalanche activity during the 1/13 cycle.

• Saw debris and/ or crowns from 15-20 natural avalanches in the upper Whitefish River valley. 6-8 ran to or across the snowmobile trail to Red Meadow lake. 
• Small to large, with a few very large. Slab and loose snow avalanches. 
• Most of the activity we saw was at mid-elevations - 5000-6000 feet. However, many crowns were shallow - 8-18" - and some had beed drifted in with snow subsequent to release, making them hard to see.
• It's possible that additional activity occurred at upper elevations, near the crest of the range, and had also filled in. We didn't see any large/ long crowns in this windward terrain. 
• As near as we could tell, all slides were direct-action slides that resulted from rapid loading or rain on new snow. We found no rain crust and very little new snow on the debris we reached, indicating those slides failed very late in the storm. Snow-covered crowns and debris elsewhere suggested some slides ran earlier in the cycle. 
• The snow surface consisted of about 1 cm of low-density snow, sometimes rimed, sitting on a very hard crust. The crust was 1-2 cm thick at the trailhead and grew thicker, to 5-7 cm, as we approached the crest of the range, where it likely rained harder and/ or for longer.
• Other riders reported more slides in the Stillwater River valley to the north. 

The crust made for tricky riding. Supportable with a flat sled, very grabby trying to get a sled on edge. 

Here is a video about what we saw: https://youtu.be/wuj1Mjv-CSM