Okay, so, really not an avalanche, but still super interesting.  This is a glide crack.  I've never seen one here before, but, its presence makes sense; we've got a pretty homogenous snowpack and the terrain underlying the 'pack here is a rock slab.  Best to give this thing a wide berth.  it's pretty difficult to say when this thing will continue down hill.  Might be the next warming spell, might be June.  The point is, we just don't know.