When Do Rain And Flood Become Plural?

I've been questioning myself this question for sometime now. I know rain is rain and flood is flood.

I just that I have no bloody idea when should I use the singular or plural form? Of course I should use the plural form if I'm referring of the rain occurred many times in a day; or flood in plural if I'm referring to several flooding that happened in the past.

But I've seen the plural form of the same rain and the same flood being used in some newsreports.

I guess, it's time to do some research.

Number, Majority, Total

Ok, this is weird. The article the and a can either make a noun singular or plural. So, while the total, the majority, the number are singulars; a number, a total, a majority, are plurals.

Another thing, in what situation should a noun be plural or singluar the qualifier "any"?

One general rules, when it's in the negative, it's plural, i.e it didn't show any irregularities. But also depends on whether you are refering to one or more subjects after the word "any".