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 atmosphere contains an enormous amount of moisture that circulates around the globe, shown here in this imagery. However, not all of the moisture actually condenses into rain, sleet or snow, since the right balance of pressure and temperature is needed to create precipitation. The NOAA Global Forecast System weather model is used to predict the total precipitable water content of the atmosphere—the amount of water that could theoretically precipitate if the atmospheric conditions were ideal. Visible in this data imagery are the bands of moisture that encircle the equator, along with the atmospheric rivers that transport moisture from these areas to higher latitudes. The model updates every six hours and provides forecasts for 10 days (240 hours) out from the start time, in three-hour time increments..