The act of having a "wish" or "desire" for a weather event to intensify. In hurricanes, it is a wish for the hurricane to intensify or increase it's stats.
Wishcasting:
Hurricane Harvey will get upgraded to a Category 5!
when you're holding up your phone and making faces at it, as though you are taking a selfie, but you're really taking a picture of the person across from you or the wall or anything else that seems interesting but you don't want to be caught dead taking a picture of.
This action is often made more convincing by wiggling the eyebrows or opening the mouth, to pretend you're trying to get a Snapchat filter to work.