[M-IS04] Extreme Weather and Water-Related Disasters in Asia

[MIS04-02] Impacts of Successive Multiple Tropical Cyclones on the Philippines

*Gerry Bagtasa¹, Alyssa Dawn M. Castillo¹ (1.UP - IESM)

Keywords:tropical cyclones, multiple tropical cyclone events, the Philippines, impacts

Tropical cyclones (TCs) are the most destructive and costly hazard that regularly affect the Philippines. In a span of a month in October-November 2024, the island of Luzon in the northern Philippines was hit by 6 consecutive TCs, which posed a challenge in disaster risk reduction efforts and left serious socioeconomic impacts on the country. In the present study, we investigated the climatology of multiple TC events (MTCE) that have impacted the Philippines, as well as countries of the Asia Pacific region. Of the 1,141 TCs that formed in the western North Pacific (WNP) basin from 1980-2024, 454 were single TCs while 267 TCs coincided with at least 1 other TC in the WNP, totaling 687 MTCEs. In terms of their impacts, Japan has the highest proportion of landfalling MTCEs with 51% of all landfalling TCs belonging to an MTCE, followed by the Philippines with 50% and China with 48%. The succeeding TCs in an MTCE tend to be more intense than the first landfalling TCs for most countries, however, the average spatial and temporal separation of TC landfall points in Japan is 792 km and 5.5 days, respectively, and 917 km and 6.8 days, respectively, for China, which means succeeding TCs likely affect different regions. On the other hand, the mean TC separation for the Philippines is 385 km and 5.4 days. While various prior literature points to mixed Rossby-gravity waves supporting MTCEs due to the zonal and time separation of TCs in MTCEs, we found that only 41% of succeeding TCs are formed by Rossby wave energy dispersion from pre-existing TCs. The other 23%, 16%, and 12% are due to easterly waves, confluence region, and shearline, respectively.