It's a thing call the Plainfield Syndrome. It's the idea that it's better to issue too many warnings and be wrong then to miss that one crucial warning at the cost of human life.

That's why they man Irene such a big deal and sure wasn't as bad as they thought in new york but other place got it bad.

So if the NWS issues a warning and you don't want to follow it and it is as bad as they said then you can't say they didn't warn you.