Marufish World of Disaster PreventionLa Nina STAYS, Negative IOD Coming

BOM, 10 May 2022

La Niña maintains strength

The 2021–22 La Niña continues in the tropical Pacific, with little change in strength in the past few weeks.

Several indicators of La Niña, including tropical Pacific sea surface temperatures, cloudiness near the Date Line, and the Southern Oscillation Index (SOI), have maintained or slightly increased their strength over the past fortnight. However, beneath the surface of the tropical Pacific, waters have warmed closer to neutral El Niño–Southern Oscillation (ENSO) levels.

Most climate models surveyed by the Bureau indicate a return to neutral ENSO by the early southern hemisphere winter. Only one of seven models continues La Niña conditions through the southern winter. La Niña conditions increase the chances of above average rainfall for much of eastern Australia, while neutral ENSO has little influence on rainfall patterns.

Indian Ocean

The Indian Ocean Dipole (IOD) is currently neutral. The latest IOD index value for the week ending 8 May 2022 was +0.13 °C. Surface waters are warmer than average over most of the Indian Ocean for the week ending 8 May 2022.

All five international climate models surveyed by the Bureau indicate a negative IOD event could develop by late autumn or early winter, with several forecasting strong negative values of the IOD index by August.

However, model outlooks issued at this time of year have low accuracy (skill) beyond autumn. The Bureau will continue to monitor model outlooks as winter approaches.