Under-achieving November Rainfall in Australia.

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A La Nina climate is normally wetter than normal across northern and eastern Australia. However, November has been dry in these sectors. Contributing to the dryness is the subsidence phase of the Madden Julian oscillation at the tropical longitudes of Australia.

Discussion: So far in November, rainfall rate anomalies across northern and eastern Australia have been somewhat drier than normal (Fig. 1). The drier than normal regime is a big surprise given wet climate forecasts due to La Nina presence. The cause of the dry surprise is presence of the subsidence phase of the Madden Julian oscillation (MJO) at the Australian longitude suppressing rainfall risk in Australia (Fig. 2). The MJO has persisted in the Atlantic tropics for late autumn and responsible for late season North Atlantic basin tropical cyclones. The MJO is expected to shift eastward but weaken the next 2 weeks. The ECM ENS maintains a dry pattern across Eastern Australia the next 15 days (Fig. 3).

Fig. 1: The Australia precipitation rate anomalies so far in November.

Fig. 2: The Madden Julian oscillation activity from the past 40 days.

Fig. 3: ECM ENS 15-day percent of normal rainfall forecast across Australia.