Seems like it's been years since it started to thunder...
It's not a good idea to be out and Penny knows this especially after Johnny's prediction, but she's been cooped up in her room with her map, Daniel, and a GPS system, keeping track of Hart's whereabouts for Torchwood and that's bound to make her go a little stir-crazy. She left Juliet a note on her door so she wouldn't have a heart attack if by chance the ordeal with Hart concluded before she got back, although no one else was similarily informed... Mostly because Juliet seems to be the primary reason she hasn't left the basement and would thus be the one sending out the search parties if she couldn't find her. Somehow Juliet thinks it would do Johnny's memory well to prevent his last vision from coming true. Penny's not exactly sure you can prevent those sorts of things, however. The universe always has a way of course-correcting itself, after all. If she's meant to die, she's meant to die.
She has a panic button around her neck, tucked into her blouse and out of view, and she's walking through the park currently, not all that far from the Conrad, really, so at least she's taking the proper precautions and not being reckless, despite everything.
Well, you know what they say- most disasters happen close to home, so it might be a moot point.