On the movement of tropical cyclones - 1954-55 season

The tracks of all tropical cyclones in the 1954-55 season in the Australian area were collected and studied. At the same time charts were made of the zonal discontinuity at the 200 mb. level, to find out what effect this had upon the tracks of the cyclones. The zonal discontinuity is the area of separation be the broad scale westerlies and the easterlies over the equatorial and tropical regions. In all of eight cases from January to March 1955, there was good relationship between the tracks followed by the storms and the position of the zonal discontinuity. With the tropical cyclone located well to the north of the discontinuity, a component of movement from east to west was maintained; with the cyclone located to the southward of the discontinuity, west to east movement eventuated. Cases where the discontinuity moved north or south of the cyclonic centre resulted in slowing-down or recurvature. With one notable exception, abrupt re curvature was not a marked feature of the seasonts cyclones, and this was associated with a persistence in position of the 200 mb. discontinuity or ridge-line.