What you need to know about flash floods and how to stay safe when they happen

PHILADELPHIA (CBS) -- Flash flooding has been not only in the headlines more and more in 2023, but has so far been the number one cause of injury, death and destruction in the area.

But what exactly are flash floods, and how do you stay safe when they happen?

Let's start with the basics: Flash flooding occurs when heavy amounts of rain falls in a short period of time -- usually less than 6 hours. Typically, the rainfall rates are 0.5-1.0 inches per hour. Lesser amounts if the ground is already saturated. In the most recent flooding, we've seen rainfall rates of over 2" per hour.

The truth is: most drownings take place in Flash Floods. Over 50% of those are in vehicles driven into flood waters! It only takes 8 inches of water to carry a vehicle away.

On Saturday night in Upper Makefield, between 6 and 7 inches fell in under one hour. The runoff funneled into the creek and resulted in a 5-foot wave of water that raced downstream tsunami-style, creating flooding which claimed the life of at least five people.

If you find yourself in an area under a flash flood warning, there are a few things you can do to keep yourself and your family safe: 

• Move immediately to higher ground.
• Monitor the media for emergency information.
• If evacuated, take only essential items.
• Do not walk through flowing water. Six inches of swiftly moving water can knock you off of your feet.
• "Turn Around, Don't Drown!" Don't drive through flooded roads. Cars can be swept away in only 1-2' feet of moving water.
• If your vehicle is trapped in rapidly moving water, stay in the vehicle.
• If the water is rising inside the vehicle, seek refuge on the roof.
• Do not drive around road barriers. Roads and bridges may be washed out or structurally unsound.

Danger doesn't end the minute a flash flood is over. Here are a few things to do in the immediate aftermath:

• Stay away from downed utility wires. Always assume a downed power line is live -- Electrocution is a flood danger; electrical currents travel through water.
• Stay out of damaged buildings and roads until they are cleared as safe by authorities.
• Watch for sharp debris after the flood, including broken glass and nails.
• Verify your water supply is safe to drink. If unsure boil water for at least one minute before drinking or using it for cooking.
• And finally, don't eat food from flooded gardens.