Greetings guys,

I need to add some lines to my original graphic, identifying the wetting season and the drying season, but I have no idea how to do it.

I made a demonstration trough paint, in the attachment, just to clarify what I'm looking for. It doesn't have to be exactly as I demonstraded, I just want to convey that idea, any suggestion?
I also uploaded the excel file, in case you guys want to play with it.
I also added the excel file.

Thanks in advance!

Original.jpgAfter.jpg