A meteorologist uses satellite imagery, air observations and computer models to predict thunderstorms. According to The Weather Channel, thunderstorm forecasting is very similar to the forecasting used to predict tornadoes.
Meteorologists monitor the atmosphere for signs of thunderstorms so that they can issue warnings in areas where severe storms form. The surface and upper air observations are studied to find areas of low-level moisture and instability, and to determine how the movement of winds might influence storm development. Computer models use various data points to predict the formation of a thunderstorm ahead of time, whereas radar and satellites are used to track the storms once they form.
The computer programs used to create forecast models and predict the development of thunderstorms are called numerical prediction programs. These programs predict future weather using physics and dynamics to describe the atmosphere's behavior mathematically. Since weather is inherently unpredictable, meteorologists also use a technique called ensemble forecasting to predict thunderstorms. This method uses a supercomputer to run several models at one time to observe weather patterns.
Meteorologists also use their experience, knowledge, persistence and eyes to fine-tune their forecasts. According to Flight Safety Foundation, meteorologists must know how convection operates in order to forecast thunderstorms.