Tropical Climate Update

Ex-tropical cyclone Esther delivers widespread rain to northern Australia

While the system that was tropical cyclone Ferdinand had no direct influence on the Australian mainland, ex-tropical cyclone Esther contributed to significant rainfall totals across much of northern Australia during the past week. Ferdinand remained well off the coast of northern Western Australia (WA) throughout its lifetime, peaking in intensity as a severe, category 3 tropical cyclone, prior to dissipating over the Indian Ocean on 29 February. Esther tracked westwards across northern Australia after making landfall as a category 1 system along the southern Gulf of Carpentaria coast last week. Widespread rainfall totals in excess of 200 mm were observed between the Gulf of Carpentaria coast near the Queensland–Northern Territory (NT) border, westwards to the Kimberley coast in northwest WA. Peak rainfall totals around 350 mm were observed in both WA and the NT for the week ending 2 March. Ex-tropical cyclone Esther remains over land and while the system isn't expected to redevelop back to tropical cyclone intensity, it is expected to generate further widespread rain for parts of central and south-eastern Australia in the coming week.

Climate models indicate the probability of a tropical cyclone forming in the Australian region during the next week is average to below average.

Madden–Julian Oscillation expected to strengthen over Australian region

A pulse of the Madden–Julian Oscillation (MJO) is predicted to strengthen slightly over Australian longitudes in the coming week. While this MJO pulse is forecast to remain weak, an MJO pulse in this region at this time of the year typically leads to above-average cloudiness and rainfall across parts of northern Australia and the southern Maritime Continent.

Read more about the Madden–Julian Oscillation

Monsoon break conditions return to Australia

The active monsoon trough which assisted the recent development of TCs Esther and Ferdinand has recently dissipated due to ex-TC Esther moving further south over the Australian mainland. As a result, monsoon break conditions are expected to dominate northern Australia for the short to medium term. During monsoon break periods, rainfall typically decreases and tends to be below average over northern Australia. The latest Bureau climate outlooks predict drier and warmer than average conditions for much of northern Australia in the next few weeks, although much of northern Queensland is predicted to have a wetter-than-average period between 7 and 13 March.

Monsoon break conditions are expected to develop despite the forecast presence of an MJO pulse in a region typically favourable for enhanced rainfall across northern Australia. This appears to be related to the relatively low strength of the MJO as well as an absence of regional weather conditions which might be expected to transport significant moisture across northern Australia.