Another Historic Month of Rainfall in Australia

Highlight: More wet weather ahead for Australia but less excessive.

Fig. 1-2: Australia percent of normal rainfall from last week and the mega-cluster 15-day percent of normal rainfall outlook.

Discussion: Last week, heavy rainfall was observed in parts of northern and southeast Queensland plus southeast New South Wales (Fig. 1). Amounts were not as excessive as rainfall events observed in October (Fig. 2). The extreme rainfall amount in October is attributed to the combination of negative Indian Ocean dipole (-IOD) and La Nina regimes enhanced by very warm SSTA north and northeast of Australia.

In the 15-day outlook, a persistent upper-level low-pressure trough is located over the western half of Australia (Fig. 3). This feature causes additional periods of wet weather, mostly in the South this week (Fig. 4) and more widespread in the 6-10-day period (Fig. 5). Wettest weather is across Northern Australia in the extended range (Fig. 6)

Fig. 3-6: The ECM ENS 15-day upper air forecast across Australia and the mega-cluster ensemble 15-day percent of normal rainfall forecast.