Wednesday, May 11, 2011

Flash Flooding

A series of thunderstorms dumped heavy rainfall over the southern sections of our viewing area overnight.   From around midnight through 5 a.m., heavy rain fell over much of Putnam, Allen & Hardin counties. 

Our StormTrack 11 doppler estimates that a few spots received between 3 and 6 inches of rain.  You can see in the snapshot below, a bulls-eye of orange stretches across eastern Allen and western Hardin county, where isolated 6"+ amounts occurred.

This heavy rainfall was the result of something called "training".  It is when waves of thunderstorms move over the same area repeatedly -- like train cars on a track passing the same area over and over.  Many flash flood events occur from this phenomenon.

Flooding causes the most severe weather deaths, and many of those deaths result in people staying in their cars.  The National Weather Service has a flood safety slogan called "Turn Around, Don't Drown".  Flood water can sometimes wash away a road, so the water may be a lot deeper than you think.  About one foot of water can make about 1,500 pounds buoyant, so a couple feet of water will float most cars.

Flood deaths also are a result from people in a low-lying area, like a bridge underpass, that gets inundated with water in a short period of time.  The bottom line is, when very heavy rain occurs, being in a car is not a very safe place to be.