Breakdown: Why there’s a difference in flood warnings

Why there’s a difference in flood warnings?

MEMPHIS, Tenn. (WMC) - There are so many warnings when it comes to flooding. There are flood watches, advisories, and warnings, in addition, there are urban and small stream floods, river floods, flash floods which can all be confusing. Flooding occurs in every U.S. state and territory and is a threat experienced anywhere in the world that receives rain.

In the U.S. floods kill more people each year than tornadoes, hurricanes or lightning, so it’s important to know the terms. Here is a breakdown of what it all means and hopefully clear up any confusion.

Let’s begin with Flash floods, which are the most dangerous kind of floods because they combine the power of a flood with speed and unpredictability of moving water. Flash floods occur when excessive water fills normally dry creeks or river beds which can cause a rapid rise of water in a short period of time. They can happen with little or no warning.

Flood/Areal flood is when a specific area is expected to flood around six hours or longer following the start of the rain. This may prompt an areal flood warning. This is different from a flash flood because it will take a longer period to develop, but can still pose a serious threat to life and property. Action may be needed but it may not need to be an immediate action because it develops over a longer period of time, unlike a flash flood.

River flooding is another type of flooding but it can be issued without there being any rain. This is due to other areas that get rain and that rain could run downstream. Most major rivers and larger creeks contain gauges that are monitored when it rains. River flooding is a slower process and usually affects a specific area depending on the flood stage. River flood warnings are normally issued days in advance.

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