The fact that CAPE is observed in nature implies that CAPE is not always directly 'consumed' by storms as soon as the CAPE forms. From this, it may be inferred that an additional requirement is usually necessary for storms to form.

Both on small and large scales convective initiation is associated with upward vertical motion or lift. A broad range of processes on the synoptic scale to the scale of the convection itself can create that lift. In the context of parcel theory this can be described as follows: Instability is often not released because of convective inhibition (CIN). However, if parcels acquire sufficient vertical velocity (kinetic energy) below the CIN-bearing layer, they may still be able to pass through it. This may be the case with strong thermals or can occur when parcels get an upward push, for example along a gust front.

Another way to initiate convective storms is when CIN is removed. This occurs when the air-mass is subject to mesoscale or large-scale lift resulting in an adiabatic cooling of the respective layer (i.e. the air is lifted along the isentropes) so that the CIN disappears. The resulting vertical temperature profile is one that allows parcels to pass easily to their level of free convection. CIN may also disappear when the parcel's temperature and humidity increase. Several sources of lift on different scales can be distinguished, for example...

convergence lines

sea- and lake-breeze fronts

convective outflows or gust fronts

thermals and horizontal convective rolls

upslope winds

meso- or synoptic scale areas of upward motion

The smaller the system is that produces lift, the harder it usually is to forecast or diagnose its location and whether it will provide sufficient lift to initiate convective storms. In the section on multicell storms, the generation of storms along several types of boundaries is discussed.