Iowans saw plenty of snow melting in the past few days, so it’s appropriate that this is Flood Safety Awareness Week. Jeff Johnson, the warning coordination meteorologist at the National Weather Service office in Des Moines, says flash flooding is the deadliest weather phenomenon in the nation, and Iowa sees plenty of it. Johnson says they’re promoting the slogan "Turn Around, Don’t Drown."
He says the initiative tries to get folks, instead of driving through flooded roads, to stop and head back or take a different route. Never drive around barricades. Johnson says the depth of water on the roadway may not look hazardous, but he says it doesn’t take much for the current to carry your car — and you — away. He says there’s not really a rule of thumb for how much water can be on a road before it’s safe to cross.
Johnson says "That’s the problem. You don’t know how deep it is when you’re just looking at it. In general, it takes a foot or two of moving water to take a vehicle, including pickups and SUVs, and move them off the road and into the ditch. And once you’re in the ditch in running water, it’s very difficult to escape from that." River flooding is often very slow, he says, and can cause heavy damage to property, especially agricultural land. Johnson says flash flooding is a different thing entirely.
He says flash flooding is the rapid flooding you get after heavy rains or a dam break or levee failure, usually within six hours of the precipitation. He says flash floods cause most of the fatalities.