Prolonged dry weather in January/February created a persistent weak layer (PWL) of facets on the snow surface that was buried by last week's light snow. Despite record breaking heat this week, this layer remains cold, dry, and weak. It exists on northerly facing slopes as well as east facing and upper elevation southeast facing slopes. For today this PWL creates an avalanche problem where there is a cohesive slab on top of it. These places are higher elevations that either received more snow last week or received additional wind blown snow.

To be honest it's hard to believe how dry and weak this layer is until you see it and feel it with your own hands. In the photo below notice the smooth texture of the new snow on top of the rough, granular looking weak snow underneath. The trickiest part about this layer is it's distribution which will determine where avalanches occur after this weekend's snow. It is widespread on slopes generally sheltered from winds. At higher elevations, previous winds scoured the old snow surface and left this weak layer in random pockets. One slope may have it while another may not. One part of a slope may have this layer while another part of the same slope may not. Personally, I would assume that it exists everywhere.