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The El Niño Southern Oscillation (ENSO) plays a major role in the variability of Australia's climate. Periodic droughts and wet conditions follow the ENSO phases. Understanding ENSO and its effects on Australia is never more important than in the cases of extreme events such as severe droughts or flooding. In this paper, we examine changes in the basic climate state over Australia during the two extreme flooding periods

We examine the synoptics and the role of different classes of dynamical disturbances, from both observations and ensemble simulations, during of one of Australia's most severe flooding events in January 2011. We analyse ensemble simulations using the csiro Mk3L general circulation spectral model. Using wavenumber extraction techniques and dynamical mode analyses, we note the collision and convective coupling of Kelvin waves and the Madden-Julian oscillation in the Australian monsoonal region. Model simulations and the dynamical analyses are consistent with the synoptic situation, and provide a more complete explanation for the extensive precipitation impacts over Australia during January 2011.