Subseasonal prediction of Australian summer monsoon anomalies

Abstract

Subseasonal prediction of Australian summer monsoon anomalies is assessed using 30 years of retrospective forecasts from version 2 of the Predictive Ocean Atmosphere Model for Australia. Active and break monsoon rainfall episodes are associated with large-scale cyclonic westerly and anticyclonic easterly winds, respectively, for which the Madden-Julian oscillation (MJO) makes a dominant contribution and thus is a source of predictability. Although the forecast model can predict the local large-scale zonal wind anomalies for lead times beyond 4 weeks, predictive skill of the monsoon rainfall anomalies is limited to about 2 weeks. We show that improving the prediction of the MJO and its local expression in the summer monsoon leads to improved monsoon rainfall predictions at multiweek timescales.