Chasing Rainbows: trying to achieve something that is not possible or practical

“He wanted to go into show business, but friends told him to quit chasing rainbows.”

http://idioms.thefreedictionary.com/chasing+rainbows

Face Like Thunder: to have a very angry expression

“I don’t know what had happened but he had a face like thunder”

http://idioms.thefreedictionary.com/have+a+face+like+thunder

Storm In A Teacup: a small event that has been exaggerated out of proportion

http://encyclopedia.thefreedictionary.com/Storm+in+a+teacup+(idiom)