Discussion: Excessive rainfall events continue in East/Southeast Australia most-focused on the Sydney area this week. The culprit of the persistent heavy rains in East/Southeast Australia is a semi-permanent upper-level low-pressure trough (Fig. 1) present most of 2022 (so far). The attendant rainfall pattern in 2022 (so far) is extreme rain beneath the upper trough across the southeast quadrant of the nation (Fig. 2) while Northeast Australia Monsoon Rains were below normal. Helping the upper trough to produce so much rain is the entrainment of moisture-rich low-level atmosphere air present due to the warmer than normal ocean surface surrounding Australia (Fig. 3-4). Unfortunately, more heavy rain is in the forecast for East Australia according to the GFS (Fig. 5).
Fig. 1: The prevailing upper air pattern across Australia so far in 2022.
Fig. 2: The rainfall anomalies across Australia so far in 2022.
Fig. 3-4: Anomalous warm SSTA on either side of Australia helped East Australia gain heavy rains in 2022 so far.
Fig. 5: The GFS 15-day percent of normal rainfall forecast keeps East Australia wet.