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How do meteorologists predict changes in weather?

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Weather forecasting Doppler radars, such as this one operated by the U.S. National Weather Service at New Underwood, South Dakota, extract the Doppler frequency shift of the echo produced by a moving target by noting how much the frequency of the received signal differs from the frequency of the signal that was transmitted.

Meteorologists predict changes in weather by combining comprehensive atmospheric observations with objective, physics-based calculations. The process relies on two primary pillars:12

Data Collection

Accurate forecasting begins with establishing the current state of the atmosphere, known as initial conditions. Meteorologists gather data on temperature, pressure, wind, and humidity using various methods:12
* In situ measurements: Instruments located directly at the point of interest, such as radiosondes (weather balloons), surface platforms, and sensors on commercial aircraft.3
* Remote sensing: Technologies that monitor the atmosphere from a distance, including radar, lidars, and Earth-orbiting satellites.32

Numerical Weather Prediction (NWP)

Once current conditions are mapped, meteorologists use numerical weather prediction models. These are complex sets of physics-based equations solved by supercomputers to calculate how atmospheric conditions will evolve over time. The computer simulates changes in small time increments, using the output of one step as the initial condition for the next.12

While these models are highly sophisticated, meteorologists also use weather maps and their own expertise to interpret model results, especially for localized events like thunderstorms.124