Answer:

The Philippines is located in the western part of the North Pacific Ocean. This vast area encompasses many countries in Oceania and the eastern parts of Asia. Tropical cyclones can form over warm waters anywhere within this area. This poses a significant challenge to the forecasters in different countries within this region. To make monitoring easy for the forecasters, this large region of the Pacific Ocean is broken into smaller domains called "areas of responsibilities". Here, forecasters will only have to monitor those TCs that are relevant to their country.

PAGASA forecasters use three domains where they monitor, analyze and forecast tropical cyclones: the Philippine Area of Responsibility, Tropical Cyclone Advisory Domain and the Tropical Cyclone Information Domain. These domains can be visualized as "three-layered zones" that enclose the country. If a tropical cyclone is present inside these domains, PAGASA is obliged to provide information about the weather disturbance to the public. Because most tropical cyclones come from the broad expanse of ocean east of the country, the eastern boundary of each domain is farther from the Philippine Islands than the western boundary