Southwest Pacific (SWP) tropical cyclones (TCs) are inherently variable (spatially and temporally), due to the coupled ocean-atmosphere interactions of the region. In addition to the relationship between El Niño-Southern Oscillation (ENSO) and TC activity, recent research has identified the impact of other climate influences in driving spatio-temporal changes in SWP TC activity. These include the Interdecadal Pacific Oscillation (IPO), the Southern Annular Mode (SAM), the Madden Julian Oscillation (MJO) and eastern Indian Ocean sea surface temperature variability. When each of these influences is considered in combination with the various phases of ENSO, some can act to amplify or suppress (in some cases reversing) the location of TC activity, compared to analysis of ENSO alone.

Current approaches to derive seasonal SWP TC outlooks rely heavily on ENSO conditions, and less so on other large-scale climate mode influences in the region. Building on the National Institute of Water and Atmospheric Research’s (NIWA’s) current climate analogue methodology for forecasting seasonal TC counts and locations, we test the efficacy of using various climate mode pairings including ENSO-IPO, ENSO-SAM, ENSO-MJO and ENSO-eastern Indian Ocean SST variability to improve model skill. Outputs from the suite of pairings can be combined to provide a multi-modal ensemble-based outlook scheme that will enable quantification of uncertainty. This approach has the potential to improve model skill for all SWP nations, but in particular, those in the far east SWP (French Polynesia and the Cook Islands) and far west SWP (Australia and Papua New Guinea), where the typical ENSO driven TC migrations (towards the northeast during El Niño and southwest during La Niña) are significantly modulated depending on particular climate mode pairings. Capturing multi-modal variability represents a significant opportunity to improve model skill which in turn will enable improved preparation for and management of TC impacts.