Articles | Volume 7, issue 3
https://doi.org/10.5194/wcd-7-1285-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-7-1285-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
23 Jul 2026
Research article |
| 23 Jul 2026
| 23 Jul 2026
Synoptic climatology of extratropical transition of tropical cyclones over the Southern Hemisphere
Australian Research Council Centre of Excellence for the Weather of the 21st Century and School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia
Elizabeth A. Ritchie
Australian Research Council Centre of Excellence for the Weather of the 21st Century and School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia
Neil J. Holbrook
Australian Research Council Centre of Excellence for the Weather of the 21st Century and Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
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This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
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This study investigates how the extratropical transition (ET) of tropical cyclones influences downstream weather in the Southern Hemisphere. Two main ET downstream developments are identified: a propagating Rossby wave train along a strong, straight jet, and a more localised downstream ridge associated with a weaker, poleward-oriented jet. The strong ET events in the southwest Indian Ocean can increase the occurrence of high-impact weather over Australia.
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We apply a clustering approach to analyze winter jet stream variability over Australia, defining five jet configurations. We find high variability, especially in the longitudinal jet maximum. Patterns of vertical motion show the strongest ascent south of the jet maximum, coinciding with enhanced precipitation. Extreme precipitation events for six Australian capital cities are linked to either a strong or weakened jet stream, highlighting the important role of the jet in driving those events.
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The El Niño-Southern Oscillation strongly affects Australia’s rainfall, but its impacts on Australian extratropical cyclones are difficult to detect. By focusing on days when ENSO-related teleconnection patterns were established, we identified clearer changes in cyclone activity over the Tasman Sea, with more frequent cyclones during La Niña and fewer during El Niño. These results provide new insights into how large-scale climate modes influence regional weather systems.
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This study investigates how the extratropical transition (ET) of tropical cyclones influences downstream weather in the Southern Hemisphere. Two main ET downstream developments are identified: a propagating Rossby wave train along a strong, straight jet, and a more localised downstream ridge associated with a weaker, poleward-oriented jet. The strong ET events in the southwest Indian Ocean can increase the occurrence of high-impact weather over Australia.
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EGUsphere, https://doi.org/10.5194/egusphere-2026-4836, https://doi.org/10.5194/egusphere-2026-4836, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
Short summary
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We apply a clustering approach to analyze winter jet stream variability over Australia, defining five jet configurations. We find high variability, especially in the longitudinal jet maximum. Patterns of vertical motion show the strongest ascent south of the jet maximum, coinciding with enhanced precipitation. Extreme precipitation events for six Australian capital cities are linked to either a strong or weakened jet stream, highlighting the important role of the jet in driving those events.
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EGUsphere, https://doi.org/10.5194/egusphere-2026-3344, https://doi.org/10.5194/egusphere-2026-3344, 2026
This preprint is open for discussion and under review for Weather and Climate Dynamics (WCD).
Short summary
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The El Niño-Southern Oscillation strongly affects Australia’s rainfall, but its impacts on Australian extratropical cyclones are difficult to detect. By focusing on days when ENSO-related teleconnection patterns were established, we identified clearer changes in cyclone activity over the Tasman Sea, with more frequent cyclones during La Niña and fewer during El Niño. These results provide new insights into how large-scale climate modes influence regional weather systems.
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The doldrums are regions of light winds and relatively clear skies found in the tropics. They often occur during severe coral bleaching events on the Great Barrier Reef yet remain poorly understood. This study examines why the doldrums form and persist, identifying how both tropical and extratropical weather systems align to first form the doldrums and that the stalling of these weather systems prolongs the doldrums persistence.
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This paper characterizes historical (1981–2023) marine heatwaves in the tropical southwestern Pacific, where they pose a challenge for marine resource dependent Islands. Heatwaves are distinguished as a function of their spatial extent, signature at the coast, and seasonality, to allow a better understanding of their impacts on ecosystems. Marine heatwaves are getting longer and more frequent, with greater spatial extents. Our results aim to inform the Pacific Islands on their vulnerability.
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Short summary
Tropical cyclones that move into the midlatitudes become extratropical cyclones, so-called extratropical transition. In this study, we detected transition events in the Southern Hemisphere based on the model data. We found that weather patterns during the transition are different from case to case. In some cases, strong tropical cyclones interact with the midlatitude flow and lead to great changes in weather nearby.
Tropical cyclones that move into the midlatitudes become extratropical cyclones, so-called...
