Forecast

Issue Notes

The hemispheric long wave pattern has been relatively slow moving in recent weeks. There are five main troughs. Currently the most significant troughs are near the longitudes of the southwest Indian Ocean, eastern Australia, the south Pacific, South America, and the Atlantic Ocean.

Summary:

Over southern and eastern Australia the cold front events with potential to bring widespread rain are now expected about 6 July to 10 July, 25 July to 29 July, and 29 July to 2 August. Rain events originating in the tropics and moving south are possible about 6 July to 10 July, and 17 July to 21 July. Over Western Australia the strongest cold fronts should occur about 7 July to 11 July, 18 July to 22 July, and 26 July to 30 July.

Issue Notes - Issued Jun 15

ENSO status: Neutral (El Nino Watch) Sea surface temperatures (SST's) showed a slight warming during May, and remain significantly warmer than average across the equatorial Pacific. The Nino3.4 index lingered between 0.8 and 0.9 through the month of May. On the other hand, the Southern Oscillation Index (SOI) recorded a value of -0.9 in May, dropping back again into El Nino territory. Current consensus suggests an El Nino pattern across the Pacific Ocean will continue through winter and spring, with all eight international models maintaining a warmer than average Pacific Ocean through the remainder of 2019, with a 50-60% chance of an El Nino developing again later this year. The climate outlook for winter and early spring favours an overall below average rainfall outlook across southern Qld, NSW (mainly west of the Great Dividing Range), Vic, northeastern Tas and the southern SA and WA. A Positive IOD is now well established over the Indian Ocean, with five out of six international models exhibiting a moderate-to-strong event lasting until spring. During Positive IODs, central and southeastern Australia tend to see a reduction in rainfall amounts towards the second half of winter and first half of spring. SST's along the eastern seaboard remain warmer than average, increasing the risk of extreme weather events such as East Coast Lows (ECLs), which activity reaches its peak in early winter. These can bring intense periods of rainfall east of the Great Dividing Range, leading to flash flooding.