Flash Floods: The #1 Weather-Related Killer

Did you know? Flash floods are the #1 weather-related killer in the United States!

The national 30-year average for flood-related deaths is around 127 people per year. Nearly half of these flash flood fatalities are vehicle-related. Many people will underestimate the power of water and drive in flooded roadways. 

It only takes about 6 inches of water to become difficult to control your vehicle, and it takes 18 to 24 inches to sweep your car away. No matter the size of your car, fast-moving currents can easily sweep under your car and carry it. At this moment, there is nothing you can do to control your vehicle. This is why we hold on to the saying, “TURN AROUND… DON’T DROWN!”

What causes flash floods?

There are many factors that can contribute to flash flooding, however, the two key elements are rainfall intensity and duration. Slow-moving thunderstorms and training thunderstorms are the causes for most flash floods. 

Whenever there is a storm passing overhead that contains a lot of moisture, the rate of rainfall can be excessive. The intensity of the rain can be overpowering for ground soils/sewers/creeks/etc. and the rain ultimately accumulates to be too much. Heavy rainfall over a long period of time (hours, days), can also quickly saturate soils and fill up creek beds. 

Topography and soil conditions can also contribute to flash floods. Areas in hilly or mountainous terrain are more prone to flash flooding due to the nature of water runoff and nowhere for the water to go whenever heavy rainfall moves in. 

Already saturated soils have a hard time absorbing more rainfall, especially when intense rain is falling. Naturally, when no mo   re water can be absorbed, flash flooding can occur. 

Forms of flash flooding

Urban flash flooding: Whenever urbanization takes place and fields or woodlands are converted to roads, parking lots, businesses, homes, etc., this increases runoff 2 to 6 times over what would occur on the natural terrain. There is no longer room for the runoff, so where does it go? Through streets, basements, parking lots, wherever the easiest path of motion is. 

Flash flooding in creeks/gullies: Due to the small sizes of creeks and gullies, they can rapidly fill up when heavy rains persist. They can create fast-moving water very quickly and overflow their banks within minutes.

Ice jams: After a cold snap and ice is starting to break up on creeks and rivers, floating ice can accumulate at obstructions in the body of water and stop the flow of water. This can cause water to rapidly rise and spill out of its banks. 

What can you do when a flash flood warning is issued?

  • If you are in a low-lying area, seek higher ground immediately.
  • If you are driving and encounter a flooded roadway, do not drive through it. Instead, turn around and find an alternate route.
  • If you encounter a flooded area while walking, do not walk through it. You do not know what is in the water, nor do you know how strong the current is. 
  • Continue to check the media for emergency information.