Coming from a snowy part of the country (about a foot on the ground as i post this) I can relate to this. All I can say is that when it snows you've gotta start getting creative. Think outside the box and use all the resources at your disposal. Assuming that you are in school still, I would guess that your school has a basketball court? If so, that would be a great place to get some sprints in.
On the topic of med ball throws, I can't really help you there. Sorry