The 2018–19 Australian region cyclone season was an average season that saw the formation of 11 tropical cyclones, six of which intensified further to become severe tropical cyclones. The season officially began on 1 November 2018 and concluded on 30 April 2019; however, as evidenced by Tropical Low Liua in September 2018 and Tropical Cyclones Lili and Ann in May 2019, tropical cyclones can form at any time of the year. As such, any system existing between 1 July 2018 and 30 June 2019 would count towards the season total. During the season, tropical cyclones were officially monitored by the Bureau of Meteorology (BOM), the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) in Jakarta, Indonesia, and the National Weather Service of Papua New Guinea in Port Moresby. The United States' Joint Typhoon Warning Center (JTWC) in Hawaii, and other national meteorological services such as MetService in New Zealand, Météo-France at La Réunion, and the Fiji Meteorological Service (FMS), also monitored parts of the basin during the season in an unofficial capacity.
This was the first Australian tropical cyclone season since 2014–15 to feature at least six severe tropical cyclones. It was also the third season in a row to begin prior to the official commencement date of 1 November, in this instance with the development of Tropical Low Liua on 26 September 2018. The most active month was December 2018, with a total of seven tropical lows existing in the region at some time during the month. The three strongest storms of the season—Veronica, Trevor and Savannah—all developed in March 2019, and together affected all three of the Bureau of Meteorology's Australian sub-regions as severe tropical cyclones. Overall, a total of five tropical cyclones existed within each of the three sub-regions throughout the season, representing an above-average season for both the Eastern Region and the Northern Region, but a below-average season for the Western Region. The season concluded much later than usual, and well after the official ending date of 30 April. Two tropical cyclones developed during May—Lili in the eastern Indonesian archipelago and Ann in the Coral Sea—both of which made landfall as tropical lows after weakening from tropical cyclone intensity. At its peak, Ann was a Category 2 tropical cyclone, and was the strongest storm to form in the Australian region during May since Severe Tropical Cyclone Rhonda in 1997. In total, eight systems were named by the BOM during the season, with two named by the BMKG and one by the FMS.
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Seasonal forecasts Region Averagenumber Chanceof more Chanceof less Actualactivity Whole1137%63%11 Western 744%56%5 North-Western 541%59%4 Northern 346%54%5 Eastern 440%60%5Source: BOM's Seasonal Outlooks for Tropical Cyclones.
During October, ahead of the tropical cyclone season, the Bureau of Meteorology issued a tropical cyclone outlook for the upcoming 2018–19 season, which would officially run from 1 November 2018 to 30 April 2019. Seasonal forecasts were issued for the basin as a whole, as well as the Eastern, Northern and Western regions and the North-Western sub-region. The forecasts took into account various factors, including the latest neutral to weak El Niño conditions that had been observed in the tropical Pacific Ocean.
The outlooks showed that activity in the basin overall, as well as for each of its individual regions, would be near to below average. For the Western region between 90°E and 125°E, the BOM forecast that the area would also see activity below its average of 7, with a 56% chance of a below average number of tropical cyclones occurring. TCWC Perth also noted that there was a likelihood of two tropical cyclones and a significant likelihood of at least one severe tropical cyclone impacting Western Australia. For the North-Western sub-region between 105°E and 130°E, it was predicted that activity would be above average, with a 41% chance of below-average tropical cyclone activity. The Northern Territory, which was defined as being between as being 125°E and 142.5°E, had a 54% chance of an above-average season. The Eastern region between 142.5°E and 160°E was predicted to have a below-normal tropical cyclone season, with a 60% chance of below-average tropical cyclone activity.
Seasonal summary
Systems Tropical Low Liua
During September 24, the JTWC started to monitor a tropical disturbance, that had developed about to the east-northeast of Port Moresby in Papua New Guinea. The system moved southeastwards over the following few days, and was classified as a tropical depression by the Fiji Meteorological Service on 26 September while situated on the boundary between the Australian basin and the South Pacific basin. The system proceeded to intensify into a category 1 tropical cyclone on the Australian scale, and was named 'Liua' by the Fiji Meteorological Service. The system turned westwards and began tracking back towards the Australian region the next day, but was assessed as having weakened into a tropical depression prior to exiting the South Pacific basin on 28 September. After re-entering the Australian region, Ex-Tropical Cyclone Liua's weakening trend continued due to unfavourable atmospheric conditions and the cool sea surface temperatures of early spring. Dissipation of the tropical low into a remnant area of low-pressure occurred the following day over the northern Coral Sea.
While in the Australian region as a tropical low on 26 September, the system caused minor impacts in the Solomon Islands. Despite only existing as a tropical system in the Australian region for a short period of time, Ex-Tropical Cyclone Liua made the 2018–19 season the third in a row in which the region's tropical cyclone activity began prior to the official start date of 1 November.
Tropical Low Bouchra
A weak low-pressure system developed in the equatorial Indian Ocean in Météo-France's area of responsibility on 1 November and moved slowly eastwards over the following few days while showing little sign of intensification. Late on 9 November, as the developing precursor depression to Severe Cyclonic Storm Gaja in the Bay of Bengal moved further away and the competing low-level airflow convergence associated with it diminished, the system's structure organised sufficiently to be classified as a tropical disturbance by Météo-France. Soon there-afterwards, the system crossed the 90th meridian east and entered the Australian region, where it was classified by TCWC Jakarta as a tropical depression on 10 November local time. Later the same day, the JTWC assessed the developing low as having attained tropical storm status on the Saffir-Simpson Hurricane Wind Scale, and assigned the system the unofficial designation 04S. A few hours later, at 10:00 UTC, the system moved back westwards and returned to the South-West Indian Ocean basin, where it gained the name 'Bouchra' from Météo-France and underwent a twelve-hour phase of rapid intensification to severe tropical storm status.
After meandering just to the west of the South-West Indian Ocean border for a number of days, the system re-entered the Australian region late on 12 November. By this stage, the system had weakened significantly from its peak intensity, and was only at tropical low strength. The period of residence in the Australian basin proved to be short-lived once again, however, with Météo-France indicating that Ex-Tropical Cyclone Bouchra had returned to the far-eastern part of their area of responsibility early on 13 November. The very next day, the Bureau of Meteorology noted that the system had once again returned to the Australian basin, and was located approximately northwest of the Cocos Islands, marking the tropical low's third period of existence in the Australian region in just five days.
Severe Tropical Cyclone Owen
The Bureau of Meteorology noted on 29 November that a low-pressure system located over the Solomon Islands had developed into a tropical low. The following day, as the system approached Tagula Island on a south-westwards track, the Joint Typhoon Warning Center issued a tropical cyclone formation alert as the system improved in organisation. Fuelled by the warm sea surface temperatures of the Coral Sea, and aided by excellent upper outflow channels, the tropical low continued to strengthen. At 06:00 UTC on 2 December, the Bureau of Meteorology upgraded the system to a Category 1 tropical cyclone on the Australian scale, and gave it the name Owen, making it the first tropical cyclone to form in the basin during the season. Owen weakened rapidly on 4 December and was downgraded to a tropical low.
Owen continued travelling westwards over the Coral Sea as a tropical low and made landfall well north of Cardwell, Queensland early on 10 December. After entering the Gulf of Carpentaria and reorganizing, Owen reattained Category 1 intensity on 11 December. The storm then completed an anti-cyclonic loop and turned back to the east. Owen gradually began to intensify, peaking as a Category 3 severe tropical cyclone with maximum 10-minute sustained winds of . Owen made landfall near Kowanyama early on 15 December as a low-end Category 3 severe tropical cyclone and gradually weakened thereafter due to land interaction. That afternoon, Owen was downgraded to a tropical low once more. Late that day, Owen emerged into the Coral Sea once again, before transitioning into a subtropical low on 17 December. Soon afterward, the system restrengthened somewhat, before weakening again on 18 December. Afterward, Owen made a counterclockwise loop towards Australia, while steadily weakening. Owen degenerated into a remnant low on 20 December before dissipating two days later, just off the east coast of northern Queensland.
During the storm's passage over northern Queensland, Owen killed a person and produced steady rainfall throughout the region, with the highest totals predicted for the eastern coast compared to the southwestern portions of the state. Innisfail recorded a daily total of of rain on 15 December, with Cowley Beach recording , Copperlode Falls Dam west of Cairns recording and Mission Beach recording .
Tropical Cyclone Kenanga
On 14 December, a tropical low formed well southwest of Sumatra. After a period of strengthening, it received the name Kenanga as it tracked roughly southwestward. Continuing on this course, it exited the basin on 16 December and subsequently strengthened into an intense tropical cyclone in the South-West Indian Ocean basin.
Tropical Cyclone Penny
In an active late December in terms of tropical low formation, the Bureau of Meteorology noted the development of a third weak tropical low in the monsoon trough extending from the tropical waters of the Coral Sea in the east, to the Timor Sea in the west. The revival of monsoonal and related convective activity in the region was associated with a moderate-strength pulse of the Madden–Julian oscillation moving eastwards across the Maritime Continent. The tropical low, officially designated 07U, was located near the eastern coastline of Cape York Peninsula, and was assessed by the Bureau of Meteorology as having a high chance of intensifying to tropical cyclone strength within the next three days, owing to a favourable atmospheric environment.