How di Severus know where the Cloak of Invisibility was?

In Harry Potter and the Prisoner of Azkaban, Severus goes into the Shrieking Shack with Harry's Invisibility Cloak on him.

Harry's fists clenched as they watched Snape skid to a halt next to the tree, looking around. He grabbed the cloak and held it up.

How did he know where it was?