The weather was sunny in the season 5 finale teaser because it was daytime--the Black Rock was a ways off even though it was visible to the naked eye off in the distance so by the time it reached the island it was night and a storm had developed--heck Jacob might have created it in order to bring the Black Rock to the island. So no discrepancy.Yes, I believe Cuse and Lindelof confirmed it was the Black Rock, despite the odd weather discrepency between "The Incident" and "Ab Aeterno."Was it ever confirmed that that ship was the Black Rock? I remember is looking remarkably NOT like the Black Rock.