Headed up Millcreek with the intent of going up to Cabin Run via White Fir pass but ended up deciding on Yellowjacket trees. We found an unconsolidated and airy snowpack on the way up with little signs of cohesion until we got to the Ridgeline where we found isolated wind slabs and obvious signs of transport. Dropped a cornice onto an E facing slope dropping into Alexander Basin that resulted in a hard slab avalanche that managed to run a couple hundred feet of vert. Safe turns were found in wind protected areas. Included still frames of the cornice and part of the resulting slide as I only have video.