Perhaps you’ve heard the forecast using the term “training” and the caution that flash flooding could occur. This is another phenomenon which typically occurs during the slow moving weather patterns of the summer season. When colder air collides with warmer air along a front and showers develop and evolve into thunderstorms we on the ground see the result as heavy rainfall but usually of short duration.
Training refers to the fact that the battle zone between cold and warm remains stationary in an east – west direction and numerous individual cells will proceed slowly along the front in sequence. Just as anyone who has idled at a railroad crossing will know that the individual cars on the track are a repetitive sequence and there seems to be an endless number. The radar signature for these repeating thunderstorm cells is pretty much the same – one after another with each one unleashing a great deal of water.
The end result of a series of training storms is that several inches of rain may fall in a small area which will overwhelm the drains in the city. Most road and parking stormwater systems are designed for one inch of rain per hour but a series of heavy rains could easily double or triple that rate. Think twice before driving through a flooded roadway because it could well turn into a train wreck.