North aspect of Chester col

Very large (size 3+) slab avalanche on north aspect of Chester col. Appears to have been wind slab failure that stepped down all the way to the rock. Doesn’t appear to have been result of cornice fall although hard to say with no prior observation. Very large crown, didn’t see evidence of skier tracks in the area, probably happened yesterday (Friday January 21) or very early this morning. Beware the deep persistent slab, even on shady aspects!