Your Vehicle Can Be a Trap: Many Have Tried to Cross Flooded Streets and Many Have Failed

An average of 95 people died in the United States from flash floods each year from 2009 through 2018, according to the National Weather Service. That's more than triple the average death toll from lightning.

In 2018, 80 people died from flooding, and it was the number-two cause of weather-related fatalities in 2018, behind only heat.

Almost two out of every three U.S. flash flood deaths from 1995 to 2010, excluding fatalities from Hurricane Katrina, occurred in vehicles, according to Dr. Greg Forbes, former severe weather expert at The Weather Channel.

Numerous cars were swept off roads covered by floodwater in Texas during a siege of flooding in late-May and early-June 2016. A jeep was swept away by floodwaters in just minutes in New Braunfels, between San Antonio and Austin.

Later that week, a truck was taken across the Brazos River as the driver attempted to cross the river. The passengers, including one canine friend, were safe, but the truck didn't make it.

In Granbury, southwest of Dallas, the Brazos River rose more than 15 feet in less than 12 hours during a crest. The river overflowed its banks again about 24 to 36 hours later, sweeping cars and debris downriver as it reached major flood stage. 

We Aren't Learning Our Lesson

It's easy to misjudge the depth of floodwater, particularly at night. Sometimes the bridge or road masked by floodwaters may have been undermined or completely washed out. 

In some cases, the flash-flood event occurs over such a localized area, say one part of one county or city, that driving conditions may go from dry roads to high water in a matter of a few miles or within minutes.

(EXAMPLE: Louisville Metro Flooding April 2015)

According to FEMA:

- 6 inches of water will reach the bottom of most passenger cars, causing loss of control and potential stalling.- 1 foot of water will float many vehicles.- 2 feet of rushing water will carry away most vehicles, including SUVs and pickups.

According to the U.S. Geological Survey, water 1 foot deep typically exerts 500 pounds of lateral force on a vehicle.

Rising water can enter your vehicle in a manner of minutes, even seconds.

The best advice we can give is to never drive through floodwaters of unknown depth. As the National Weather Service has campaigned for years: "Turn around, don't drown!"

If you are stuck in your vehicle underwater, you need to act quickly:

- Find a pocket of trapped air, usually against the rear window or roof.- Roll a window down slowly, take a deep breath and be ready to swim.- If the window won't open, break the window with a rescue tool (Swiss Army knife, for example).

Don't Wade Through Floodwaters, Either

If floodwaters are powerful enough to float and/or trap your vehicle, trying to wade through them is also a bad idea.

Just 6 inches of flowing water can knock you off your feet. If you slip and fall face first, you might drown before you regain consciousness. This is particularly dangerous situation for babies and small children.

Flowing at just 6 mph, water exerts the same force per unit area as air blowing at EF5 tornado wind speeds, according to Dr. Forbes. Water moving at 25 mph has the pressure equivalent of wind blowing at 790 mph, faster than the speed of sound.

Forbes said the fastest floodwater speeds are thought to be around 67 mph, which may occur in steep, elevated terrain.

Not to mention, who knows what is flowing in the water besides you if you do decide to get in. 

Your Responsibility: Be Aware

Awareness of the weather can save your life in a flash flood.

Download The Weather Channel's app for your smartphone and tablet or use NOAA Weather Radio to make sure you have a method of receiving flood watches and warnings.

Next time there is a risk of flash flooding, take it seriously. Stay out of the water. Don't become a statistic.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.