Raining Up
the opposite of rianing down; rain water shoots up from the ground into the sky.
its really raining up out there
Raining up a dog's ass
When it rains so hard that the rain is bouncing off the sidewalk and potentially up a dog's ass.
Be sure to bring an umbrella, the weatherman said there's a 70% chance that it will be raining up a dog's ass by this evening.