Two factors are necessary for precipitation which are saturated air and lifting of that saturated air. Convective thunderstorm development requires a third necessary ingredient which is instability. Instability creates an environment in which air will rise quickly on its own like a helium balloon rising through the air. Lifting refers to forced dynamic lifting which is typically much slower than convective lifting. Often dynamic and convective lifting work in tandem. Instability without lifting will often not lead to storms. This is because air often first needs to be lifted to an elevation at which the instability begins. For example, in a surface based convective situation, the instability may be between 800 and 300 millibars. The air must first be force lifted from the surface to 800 millibars by for example a low level convergence mechanism before it will be able to convectively lift thereafter. Weather forecasters look at the ingredients of moisture, lift and instability and where they are in the atmosphere in order to forecast the development and timing of convective storms.