Tropical Climate Update

First Australian Category 5 cyclone impact since 2015

Tropical Cyclone (TC) Ilsa crossed the Pilbara coast of Western Australia (WA) as a Category 5 system around midnight, early on Friday 14 April (WA local time). The last time a Category 5 system made landfall on Australian territory was in February 2015, when TC Marcia impacted the Queensland coast near the central Queensland town of Rockhampton. TC Laurence was the last system prior to Ilsa to make landfall on the WA coast at Category 5 intensity in December 2009, crossing near Wallal in the Pilbara region.

Ilsa crossed the coast in a sparsely populated region but caused major damage to the Pardoo Roadhouse and the surrounding environment. Prior to making landfall on the mainland, Ilsa passed directly over Bedout Island, about 50 km offshore from the coastal crossing site, where wind observations were recorded (provisionally correct). The sustained wind speed (10-minute mean) of 218 km/h was the highest recorded by the Bureau observation network, as was the maximum wind-gust speed (3-second mean) of 289 km/h. A minimum mean sea-level pressure reading of 931.2 hPa was also recorded at Bedout Island.

There are currently no indications of TC formation in the Australia region in the coming week from weather models.

Madden–Julian Oscillation over the Western Pacific

A pulse of the Madden–Julian Oscillation (MJO) is currently tracking eastwards over the central Pacific region. Most climate models forecast this moderately strong pulse to track further east in the coming week, before weakening in about 10 days.

An MJO pulse over the tropical central and eastern Pacific at this time of the year typically leads to suppressed rainfall across northern Australia. The risk of tropical low and tropical cyclone development is usually below average when the MJO is in this area.

Read more about the Madden–Julian Oscillation and Climate Driver Update

Widespread rainfall unlikely for northern Australia

Based on the MJO and other short-term climate forecasts, as well as the late stage of the wet season (northern wet season officially ends 30 April), it appears unlikely that conditions will become favourable for widespread rainfall across northern Australia in the short to medium term. Any widespread rainfall would only be expected if a renewed burst of monsoonal conditions developed across northern Australia, and this is highly unlikely for the remainder of the current wet season.