Natural Wind Slab Avalanches on Castle Peak

We observed a natural wind slab avalanche on the North side of Castle Peak today at 8900' just below the summit rocks.  From our vantage point it was hard to get an accurate assessment of this avalanche with width and length.  The crown line and avalanche debris appeared to be partially covered up by snow or by additional blowing snow in the early morning hours.  The crown line appeared to be 2' deep with wide propagation under the peak and we sized it at D2.  The wide propagation made us think about the buried surface hoar before this storm cycle, but could not confirm that was the cause.  The avalanche could have been triggered by a cornice collapse off of the ridge.  Another small wind slab avalanche was also observed around 8000' on the south ridge of Castle that was triggered by a cornice collapse and had some partial snow coverage.