Читать книгу Weather For Dummies - John D. Cox - Страница 22

A major weather-related killer in the United States is flooding — not the winds of a hurricane or a tornado — and the especially dangerous circumstance of high water has its own set of National Weather Service bulletins.

A flood is called a flash flood because it is sudden. It takes place within a few minutes or a few hours of heavy rainfall or some other event like a dam break or a river levee failure. Most flash flooding is caused by torrential rains from thunderstorms or the rains of hurricanes or tropical storms.

Every state in the United States has been hit by flooding of one kind or another. Rivers flood sometimes in the spring when runoff from heavy rains combines with water from melting snow, although floods can happen any time of year. Along coastlines, the winds of powerful storms can generate big waves and high tides and storm surges that cause coastal flooding. The streets of every city can fill with water of urban flooding when circumstances are just right — or just wrong!

The National Weather Service issues these special flood warnings:

  A Flash Flood Watch or Flood Watch is issued when flooding is possible. Be alert to signs of flooding and be ready to evacuate to higher ground.

 A Flash Flood Warning or Flood Warning means flooding has been reported or is imminent. It is time to act, and to act quickly, to save yourself.

 An Urban and Small Stream Advisory alerts you to the fact that flooding is occurring on some small streams or streets and low-lying areas such as underpasses and storm drains.

 A Flash Flood Statement or Flood Statement contains follow-up information about a flood event.