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How do numerical weather prediction models work?
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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.
Numerical weather prediction (NWP) models function by using objective, physics-based mathematical models to calculate future changes in the atmosphere. Rather than relying on rules of thumb, these models solve complex equations to predict shifts in pressure, temperature, wind, and humidity.1
The process operates through the following steps:
- Initialization: Data is collected globally via systems like satellites and weather balloons to establish the current state of the atmosphere, creating an initial weather map.12
- Calculation: Supercomputers solve the model's equations for various segments of the map to determine how conditions will change over a short interval, such as 10 minutes.12
- Iteration: The calculated changes are added to the initial conditions to generate a new map for the next time step. This new map then serves as the starting point for the subsequent calculation.1
- Forecasting: This iterative process is repeated step-by-step to project weather conditions into the future.1
While highly effective, these models are limited by the accumulation of small calculation errors over time, which eventually reduce the accuracy of long-range predictions.1