A cross section of the synoptic environment of MCSs along the leading edge of a frontal cloud band is characterised by the following features:

• Isentropes of equivalent potential temperature show an unstable stratified troposphere within the lower and mid-levels of the troposphere, which is mostly superadiabatic in the lower layers.
• The vertical distribution of temperature advection is characterised by CA at middle and higher levels indicating cold air overrunning the frontal air mass. This distribution means that the troposphere becomes unstably stratified.
• Fields of divergence indicate convergence within the lower and mid-levels. In the case of pre frontal MCS development, the convergence is part of the frontal circulation cell and has a distinct pre frontal maximum, indicating strong ascent.

The above images show cross sections across the frontal cloud band and the MCSs which have developed ahead of it in the warm air. The MCSs are characterised by high pixel values in the IR as well as in the WV image. Isentropes in this area indicate an unstable stratified troposphere.

It should be noted that the field of divergence is not so pronounced as in the previous example. However, weak divergence in the lower and weak convergence in the upper layers of the troposphere are indicated in the area of the MCS.