Extreme Rain Risk in Australia Fading; Early Season TC’s Expected

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Fig. 1-2: Latest IOD and ENSO forecasts from Australia Bureau of Meteorology.

Discussion: The Australia Bureau of Meteorology (ABOM) is forecasting the current negative phase of the Indian Ocean Dipole (-IOD) to weaken rapidly becoming neutral by December (Fig. 1). Climate Impact Company has previously stated the 3rd peak of La Nina during the 2020-22 cold ENSO regime is occurring now and was caused in-part by developing -IOD in AUG/SEP/OCT 2022. Therefore, the demise of La Nina should follow the collapse of -IOD. According to ABOM, La Nina decelerates quickly during late 2022/early 2023 shifting into neutral phase (Fig. 2).

Previously, Climate Impact Company precipitation outlooks for Australia in November (Fig. 3) and DEC/JAN/FEB 2022-23 (Fig. 4) indicated a mix of both dry and wet anomalies. Some dryness was forecast anticipating the demise of the wet climate producing -IOD/La Nina regimes. ABOM now agrees with this scenario. In fact, ABOM indicated a possible drought developing over northwest/north-central Australia during summertime hinted at by the CIC summer outlook. The tendency for extreme wet weather in Australia is getting ready to ease!

Fig. 3-4: Previously issued Climate Impact Company November 2022 and DEC/JAN/FEB 2022-23 precipitation anomaly forecasts for Australia.

On a separate note, the Australia tropical cyclone season began November 1st. Early season tropical cyclones are relatively rare. However, due to the excessive warm SSTA north and northeast of Australia (Fig. 5) early season tropical cyclones are expected this year. Consequently, seasonal tropical cyclone activity is likely to also be above normal (>11 tropical systems).

Fig. 5: Unusually warm SSTA are present north and northeast of Australia.