The intense rainfall caused by the southwest monsoon (habagat) enhanced by typhoon Carina (Gaemi) is considered a “precursory sign” of the looming La Niña, said Ana Liza Solis, Chief of the Climate Monitoring and Prediction Section of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA).

In a climate forum, Solis said that while the current conditions are ENSO-neutral (El Niño Southern Oscillation-neutral), where neither La Niña nor El Niño is present, the current weather patterns suggest that La Niña may be approaching.

PAGASA said there is a 70 percent chance of La Niña developing during the August-September-October season.

“We are observing sustained cooling in the Central and Eastern Equatorial Pacific while warming trends are emerging in the western Pacific, close to the Philippines," Solis said in Filipino.

She said this “seesaw pattern” is an early sign of La Niña, characterized by cooler conditions in the central Pacific and warmer conditions in the western Pacific.

Solis explained that this pattern is creating favorable conditions for increased convective activity, which can lead to more frequent rainfall events.

“The warming of the waters in the western Pacific enhances the likelihood of tropical cyclone formation and activates the intertropical convergence zone,” she said.

“These factors increase the chances of low pressure areas or tropical cyclones affecting the country,” she added.

Solis pointed out that the combination of the habagat and typhoon Carina’s rainfall, along with the observed oceanic changes, suggest that the country could see significant weather events associated with La Niña in the coming months.

‘Above-normal’ rainfall

PAGASA Senior Weather Specialist Rusy Abastillas said most of the country may experience generally near to above-normal rainfall, particularly from October to December.

She said many provinces may have rainfall amounts exceeding 120 percent of the average for those months.

In October, 39 provinces may experience near-normal rainfall, while 45 provinces could see above-normal rainfall.

In November, 69 provinces are expected to have near-normal rainfall, with 14 provinces receiving above-normal rainfall.

By December, 49 provinces may experience near-normal rainfall, while 35 provinces could receive above-normal rainfall.

Abastillas said more areas in the eastern part of the Philippines may experience near to above-average rainfall during these months, coinciding with the northeast monsoon, or “amihan” season.

PAGASA also projected that the country may have two or three tropical cyclones in October, one or two in November, and one or two in December.

“These are the things we need to prepare for, and the last quarter of this year is very critical due to the looming La Niña,” Solis said.