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Geosciences LibreTexts

20: Numerical Weather Prediction (NWP)

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  • Most weather forecasts are made by computer, and some of these forecasts are further enhanced by humans. Computers can keep track of myriad complex nonlinear interactions among winds, temperature, and moisture at thousands of locations and altitudes around the world — an impossible task for humans. Also, data observation, collection, analysis, display and dissemination are mostly automated.

    Fig. 20.1 shows an automated forecast. Produced by computer, this meteogram (graph of weather vs. time for one location) is easier for non-meteorologists to interpret than weather maps. But to produce such forecasts, the equations describing the atmosphere must first be solved.

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    Figure 20.1 Two-day weather forecast for Jackson, Mississippi USA, plotted as a meteogram (time series), based on initial conditions valid at 12 UTC on 31 Oct 2015. (a) Temperature & dew-point (°F), (b) winds, (c) humidity, precipitation, cloud-cover, (d) rainfall amounts, (e) thunderstorm likelihood, (f) probability of precipitation > 0.25 inch. Produced by US NWS.