"Floods are the most common and widespread of all weather-related natural disasters...Flooding occurs in every U.S. state and territory, and is a threat experienced anywhere in the world that receives rain." (https://www.nssl.noaa.gov/education/svrwx101/floods/)

If they were going to plan for any kind of dangerous weather, flooding should have been very high up on that list.

People tend to take flash flood warnings way less seriously than tornado or severe thunderstorm warnings. I guess that people think of dangerous floods as being something much more obvious and dramatic than a street puddle just one foot deep, but flooding is no joke.

"Turn Around Don't Drown" PSA (https://www.youtube.com/watch?v=eI6mIlHKrVY)

Any given person might only experience a single flooded roadway or two in their lifetime. But that doesn't mean that there aren't tens of thousands of people exposed to flooded roadways every year. Something can be individually uncommon and yet frequent in absolute terms.