Due to the supportability of the Christmas Eve Rain Crust (CERC) in the majority of terrain, it's unlikely that you can trigger a slab avalanche on the persistent weak layer. However, if you did, it has the potential to be a large, destructive, and potentially fatal avalanche.
Today, we bumped the likelihood of the PWL down to unlikely. This means that slabs running on weak snow below the CERC can range from unreactive to stubborn, however we want to stress that this does NOT mean that these are entirely off the menu if you head to just the wrong spot. The PWL is largely dependent on the supportability of the CERC above it. In higher, wind-exposed, W-N-E terrain where the snowpack may be thinner, the CERC may prove less supportable. These areas are most suspect for triggering a large slide. Some mid-elevation slopes fit this bill as well.
Need some proof? Yesterday, riders in Hidden Canyon triggered a second slab avalanche failing on the PWL at the ground on the exact same slope a slide ran on the PWL on Tuesday. The second skier on the slope triggered the slide.

On December 30th, Dave Kelly visited the Sunset Peak avalanche. His observations are a bullseye for understanding this setup right now. The Sunset Peak bed surface is a sober reminder of what’s at stake, where a thin veil of snow masks the rock grinder you’d be dragged through