2002 Annual

Monday, 14 January 2002: 11:30 AM
The Australian east coast sub-tropical storm of March 89, 2001: synoptic analysis and data assimilation experiments at landfall
Lance M. Leslie, University of New South Wales, Sydney, NSW, Australia; and J. LeMarshall, M. S. Speer, and R. F. Abbey
A low pressure system approached the Australian east coast at latitude 28 deg. S approximately. It made landfall early on March 9, 2001 as a cyclonic system equivalent to a category 2 TC in terms of its strength. This kind of event is rare and potentially devastating. At landfall, wind speeds averaged over 50 knots and 24 hr rainfall totals exceeded 400 mm. There is still ongoing discussion whether the system should be re-classified as a named TC, and we hope to contribute to that debate.

The extra-tropical lifecycle of the storm was almost one week and its predicted path and intensity were poorly handled by all operational models except the US MRF model, which forecast a weak low to move over the northern New South Wales coast.

In this study, there are two aims. The first aim is to perform a synoptic analysis of the lifecycle of the storm from its beginnings as a weak low in the Tasman Sea, to its landfall and eventual dissipation over land. The second aim is to use all available data, augmented by high resolution research data, to carry out a series of numerical experiments on its track and structure.

It was found that using high resolution data and data assimilation plus initialisation, the tracks, intensity and rainfall were well predicted. In particular, landfall was predicted up to four days ahead. Our conclusion concerning the classification of the system is that it should be a named storm.

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