Structure and Evolution of North Australian Cloud Lines Observed during AMEX Phase I

Abstract

North Australian Clouds Lines are distinctive, squall-line phenomena that occur in easterly flow across northern Australia. Three basic types have been identified, ranging from a long, narrow line of convective clouds (Type 1) to a severe squall line (Type 3). In this paper we examine a group of Type 1 lines, which occurred during the first phase of the Australian Monsoon Experiment (AMEX). The lines occurred in an ambient easterly flow with a distinct maximum near 850 hPa. Most of the lines developed on the western side of deep convective cells along the sea-breeze front in a manner that had substantial similarities to the African squall-line development described by Bolton. The resolvable structure resembled a shallow version of the Moncrieff–Miller squall line.