Discussion: Positive phase of the Indian Ocean Dipole (+IOD) coupled with developing El Nino combine to historically produce a dry climate across much of Australia during late spring/early summer. Much of Australia is already in an intense drought condition. Additional dryness increases the risk of unusually hot weather developing as summertime is approaching. The first +IOD/El Nino inspired heat wave is ahead for late October/early November.
On November 1st a gigantic high pressure ridge crests over Western Australia and shifts ever-so-slowly eastward into eastern Australia by November 5th (Fig. 1-2). Given the potential temperature at ground level produced by this unusually strong high pressure zone coupled with expansive worsening drought excessive heat will occur.
Fig. 1-2: The operational GFS (model) projects a strong upper ridge pattern across Australia in early November.
The evolving super heat peaks in intensity November 2-3 when maximum temperatures are forecast to exceed the 100-110F range across about half of Australia (Fig. 3-4). Slowly, the anomalous heat is edging eastward and the heat core rests over southwest Queensland by Nov. 5th. The forecasts represent anomalies of +30 to +35 in Western and South Australia (Fig. 5).
Fig. 3-4: Maximum temperature forecasts exceed 100-110 across much of Australia November 2-3 and the heat is shifting slowly eastward.
Fig. 5: Temperature anomaly forecast for November 2nd across Australia by the operational GFS (model).
Developing El Nino in the central/eastern equatorial Pacific (Fig. 6) is expected to intensify during southern hemisphere summer. El Nino is a dry climate influence on Australia. The +IOD regime in the Indian Ocean (Fig. 7) is forecast by Bureau of Meteorology/Australia to last another 3 months. Additional intense heat waves are likely well into the summer season across Australia causing life threatening conditions including brush fires and crop damage.
Fig. 6: El Nino is developing in the central/east equatorial Pacific Ocean. The core of the anomalous heat both at surface and subsurface is near and just east of the Dateline. A weak El Nino Modoki could emerge at least initially for El Nino 2018-19.
Fig. 7: The positive phase of the Indian Ocean Dipole is present.