Why Is the Radar Sometimes Wrong?

Doppler Radar is a valuable tool that meteorologists frequently use to look inside a storm and forecast the weather.

A weather radar follows some of the same principles at a flashlight. While a flashlight uses rays of light to detect objects in the dark, radars detect objects in the atmosphere using pulses of energy.

Weather radars work as both transmitters and receivers. A weather radar sends out a microwave beam then listens for echoes that bounce back from all sorts of precipitation types and intensities.

The radar then measures how much of the beam bounces back and exactly how long it takes to return. The amount of energy reflected back to the radar is proportional to the precipitation intensity.

One common feedback problem of radars is ground clutter. In this case, the radar is picking up a scattering of objects on and near the Earth's surface. It is most common when the radar is tilted at a lower level.

The radar doesn't pick up only rain, sleet, snow and hail but can also pick up and represent bugs, insects, dust and even bats!

Another common problem with Doppler Radar is how it handles precipitation that evaporates before it reaches the ground. This virga is detected by radar as normal rainfall.

To depict what is real and false correctly in this situation, be sure to use multiple radar sites and view the precipitation at different heights.

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This Day In Weather History

Lander, WY (1963)
20" snow; many livestock perished.

Havre, MT (1967)
17" of snow.

Midland, TX (1989)
101 degrees -- first 100 degree or higher reading in April since 1930.