CAPE

An acronym for Convective Available Potencial Energy (convective available potential energy). A theoretical index, calculated from the information provided by a radiosounding, that allows the magnitude of the convection responsible for storm growth to be estimated, in an environment of atmospheric instability. It is expressed in joules per kilogram (J/kg). For values between 1000 and 2000 J/kg, ambient conditions are optimal for storm activity to occur. If the CAPE index exceeds 5000 J/kg, the storms that form will be very intense, with likely hail, significant lightning activity, and violent associated wind gusts.