BLOG: Flooding terminology

BLOG: Flooding terminology
(Source: NOAA)
(Source: NOAA)

CHARLOTTE, NC (WBTV) - While Charlotte has escaped the heaviest rains the past five days (only around one to two inches in general) areas on both ends of the state have had five to ten inches of rain which prompted flooding issues around Boone, and also down east in Beaufort.

One question I get every so often is from someone wondering what the difference is between a 'Flood' warning and a 'Flash Flood' warning.

Flash Flooding gets its name from the lightning quick manner in which it can occur, thus the term 'Flash'.  Imagine a dam breaking and the wall of water rushing down a mountain slope.  It doesn't always have to be that extreme of course, but it gives you a good frame of reference.

A typical river flood takes days to develop. And once they do, they can last for days, even weeks.

The first one that comes to my mind is the Great Flood of 1993 when the Mississippi and Missouri river valleys were ravaged by severe flooding from relentless month-long rains. As these rivers reached record heights, they ruined lives in nine states. The slow-moving flood affected more than 15,000 square miles, it killed 50 people, damaged or destroyed 55,000 homes, eliminated over 30,000 jobs, and caused 12 billion dollars worth of damage.

Flash floods are usually more localized, but occur very rapidly and with little warning time making them very dangerous. Many years they are the leading cause of severe weather deaths across the country. They most often result from intense rain falling over a relatively small region. Mountainous areas contribute to the problem too as it allows the gushing water to gain a lot of speed.

Typically flooding occurs around bridges crossing creeks and streams.   It is easy to get lulled into thinking these small streams of water are harmless, but they can quickly become raging rapids of deep turbulent water.  It only takes two feet of water to float a car.

Most people who die in a flash flood are killed in their cars as they try and drive along a road covered with water. There is no way to tell how deep it is, and they suddenly find themselves in a stalled car, floating, and quickly cascading over the side of a rural bridge.

Imagine your car landing upside down in raging water.  You are submerged under water, upside down, strapped in your seatbelt and completely trapped. Of course it is an even worse situation at night.

That is why we push the phrase 'Turn Around Don't Drown' when trying to implore people to not take risks when driving under these conditions.

See the accompanying image of the cars upside in the creek after the flood was over.