John Wheeler, Published June 24 2012
Weather Talk: ‘Stalled’ thunderstorms bring torrential rainfallWhenever there is a torrential rainfall from thunderstorms, such as last week in Duluth, Minn., it is always for the same reason.
A casual observer might point the finger at unusually high humidity or a particularly strong storm. Instead, it happens when thunderstorms stall and keep forming and reforming over the same spot. Meteorologists use the casual term “training” to illustrate this process.
Any heavy thunderstorm is capable of producing rainfall rates of 2 to 4 inches an hour, but usually this type of rainfall rate only comes in short bursts over relatively small areas. Whenever the mechanism for a heavy thunderstorm is stationary over one area, a torrential rainfall is usually the outcome.
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