Tropical Cyclone Gita (2018): Impacts and Interagency Solutions for American Samoa

Tropical Cyclone Gita was an intense South Pacific tropical cyclone that impacted numerous island nations in February 2018. During its intensification phase (9-10 February), it passed near the U.S. territory of American Samoa and caused over $10 million worth of damage. Up to 17” of rainfall was observed in parts of the island territory, and approximately 90% of the main island was without power or water for over a week. Tropical Cyclone Gita then rapidly intensified and became the most intense tropical cyclone to affect Tonga in recorded history. This case presented unique challenges with regard to interagency coordination in both the preparedness and response phases of the event. The status of American Samoa as a U.S. territory with both civilian and U.S. Department of Defense assets resulted in an overlap in jurisdictional authority between the Fiji Meteorological Service and the Joint Typhoon Warning Center with regard to official forecasts. Furthermore, the complex synoptic drivers of Tropical Cyclone Gita’s track and intensity changes, including its origins in the complex South Pacific Convergence Zone, exacerbated the quantitative forecast challenge of responsible meteorological agencies as well as the qualitative assessment of risk and potential impacts by planners and first responders. Subsequently, in an effort to mitigate the impact of future tropical cyclones that may threaten the vulnerable U.S. territory, the National Weather Service (NWS) Pacific Region, with the support of the Federal Emergency Management Agency, formally hosted the Joint Typhoon Warning Center (JTWC) in an on-site outreach event to NWS meteorologists in American Samoa to improve interagency coordination efforts ahead of the next cyclone. This presentation will provide an analysis of the meteorological forecast challenges of Tropical Cyclone Gita, its impacts to American Samoa, and the outcomes of the on-site interagency outreach effort between the NWS and the JTWC that occurred in American Samoa toward the end of 2018.