Document Type
Article
Publication Date
7-14-2025
Abstract
The highest daily rainfall recorded in January at Hinatuan, Surigao del Sur, eastern Mindanao, is about 374 mm d–1, which occurred on 10 Jan 1999. This is considered the wettest day in January from 1949–2023. This study examines the meteorological conditions that led to this extreme rainfall event, which has not been explored in previous works in detail. The results of this study revealed that the high rainfall amount on this day at Hinatuan Station was due to the combined effects of the enhanced amihan, associated with the southeastward expansion of the Siberian-Mongolian high, and a weak westward-propagating vortex near Mindanao. Rainfall estimates from satellite data showed that the peak in rainfall occurred at 12 UTC on 10 Jan 1999. Back trajectory analysis of moisture sources showed that the moisture at the low levels originated from the east and southeast of Mindanao. Furthermore, enhanced northerly and easterly moisture fluxes were already contributing to the rainfall over eastern Mindanao prior to the arrival of the vortex. Using the relative vorticity (≥ 3×10−5 s−1) at 850 hPa and the surface wind (≥ 5 m s–1), the authors demonstrate the potential for tracking such weak westward propagating vortex in a gridded data set, which may be useful for improving the forecast of extreme events induced by such vortex in the Philippines.
Recommended Citation
Olaguera, L. M., & Manalo, J. (2025). Meteorological Characteristics of the 10 Jan 1999 Extreme Rainfall Event over Hinatuan, Surigao del Sur, the Philippines. Philippine Journal of Science, 154(3), 749-762. https://archium.ateneo.edu/
