A study of frontal dynamics with application to the Australian summertime cool change.

The initial conditions are an idealization of cross-sections, through a typical preexisting (finite amplitude) disturbance prior to its amplification to an intense front-trough system. Basically, they consist of a warm prefrontal N airstream embedded in a zonal shear flow in thermal wind balance. The model develops a quasi-steady surface cold front during the 24h (real time) of integration and this front is shown to have many features in common with a kinematic model of the Australian summertime cool change. The model simulation and kinematic model are compared also with a 24h prediction of a cold front using the ANMRC 3D nested-grid model. This front was a classic example of a summertime cool change in SE Australia. Broad agreement is found between the models, provided the comparison is made S of Tasmania where the front appears to be more nearly 2D.-from Authors