Yoda's Vision

In the episode "Voices", when Yoda see's a vision of Sidious killing the Jedi and Mace Windu, why is it that he's still in the cloak when in fact he was already revealed to be Sidious before these events? Now, clearly this is a future vision and in fact has not happened yet, but was Palpatine able to hide himself by clouding Yoda's vision, or was it in fact a way for the writers to save any contradictions since Yoda was unaware of Palpatine's true identity until he fights him in Episode III?

 

Mr. Dalton, I think that a way to explain that in-universe is to realize that "the dark side clouds everything" So his vision of Sidious in the cave was... cloudy and hoody to