October Novel Prep Challenge

I am trying to describe a girl looking through a window while it's raining. I want set a gloomy mood. To describe the sound of the rain, I don't want to use a cliché like tap, tap, shaking the window along with the thunder etc. Can any help me come up for a word the sound of the rain, streaming down the window? Any help would be appreciated.

I have been looking all day,
Kristina