Insider Blog: Rain rates and observed rainfall

Thunderstorms in Mid-Missouri recently brought heavy rain and some incidents of flooding to the area. These storms have been efficient rainfall producers thanks to heavy moisture in the atmosphere, some storms hit rain rates up to 6" at times. But this rate of rainfall isn't the same as what is observed in rain gauges.

The rate of rainfall is exactly that, the rate of rain that falls over a certain amount of time. Typically these are talked about in terms of inches of rainfall per hour. Storms that tracked through Mid-MO this morning were producing half-foot rain rates at times but this doesn't fall all at once. Think about car speeds, a car going 60 miles per hour doesn't travel 60 miles in an instant. In the same way, rain falling at a rate of 6 inches per hour does not all fall at once.

The rate of rainfall can be used to estimate the rain accumulation on the ground but is usually inaccurate. Storms produce rain at varying rates as they grow or weaken and their speed changes as well. Radar products for rainfall are almost always estimates, while observations from rain gauges on the ground can be more accurate.