Headed up the Y this morning around 5:30am, encountered a large debris pile (3-4') in depth at the mouth of the couloir that had ran very recently, perhaps an hour or less prior to our arrival. Seemed to be just the new snow sliding on the old surface, still moved quite a bit of snow however. Very foggy and dark so couldn't tell how far up it originated but my best guess would be at least a few hundred feet, and seems to have propagated across the entirety of the chute as well based on the size and path of the debris.