Meteorologists use many tools to predict the weather. They use past data such as temperature observations, real-time data such as radar and satellite images, and models that look into the future. Many different parameters are plotted using the numerical forecast models, which are generated using computers. The models consist of numerical equations which use current conditions as the inputs. The resulting outputs are forecasts for what is likely to happen in the future, based on those initial conditions. There are many different models that all attempt to do the same thing. The Global Forecast System model is used in this visualization.
The animated image shows forecast clouds for the next 10 days. The view is designed to look much like an orbiting astronaut would see, similar to NASA's Blue Marble dataset, except the moving clouds are showing what the latest model forecast is predicting. The GFS model includes cloud "hydrometeor" content in it output, and this data can be used to construct the clouds' visual appearance. The view is somewhat similar to what a weather satellite visible light image would show, if we could project this into the future. Bright clouds are thicker and often associated with stormy weather. This imagery is an output of the NOAA Global Forecast System weather model, which updates every six hours and provides weather predictions for 10 days out from the start time, in three-hour time increments. It directly shows whether your location on the Earth will be clear or cloudy during that time period.