Despite the increasing likelihood of El Niño development, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) warned that Western Luzon may experience “above-normal” rainfall during the southwest monsoon or “habagat” season.

El Niño is characterized by “unusually” warmer-than-average sea surface temperatures in the central and eastern equatorial Pacific that could cause negative effects, such as drought and dry spell, in some areas of the country.

PAGASA’s ENSO Alert and Warning System

However, PAGASA-Climate Monitoring and Prediction Section Chief Ana Liza Solis noted that another effect of El Niño is the occurrence of above-normal rainfall, particularly affecting the western parts of Luzon.

“Historically, we see that Luzon, particularly the western part, receives more rain during the southwest monsoon season than any other areas,” Solis said in Filipino during a public briefing on Wednesday, May 3.

Metro Manila and the western portions of Luzon and the Visayas fall under the Type 1 climate category. These areas experience two distinct seasons: dry from November to April and rainy the rest of the year.

According to Solis, the months of June and July will see above-average rainfall in the Cordillera Administrative Region, Cagayan Valley, Central Luzon, Metro Manila, Calabarzon (Cavite, Laguna, Batangas, Rizal, Quezon), Mimaropa (Oriental Mindoro, Occidental Mindoro, Marinduque, Romblon, Palawan), and Bicol Region.

“With the looming El Niño, we see that there is a reversal of rainfall pattern, where there are more rains during the monsoon in the aforementioned areas,” Solis said.

By August, September, and October, it will gradually become dry in other areas, such as Central and Eastern Visayas, Zamboanga Peninsula, Caraga, Dinagat Islands, and Bangsamoro Autonomous Region in Muslim Mindanao, she pointed out.

10-14 cyclones from May to October

Solis said that before and during El Niño, there is an unusual warming of the tropical Pacific, which is favorable for tropical cyclone formation.

Based on PAGASA’s latest forecast, 10 to 14 tropical cyclones may enter or form within the country’s area of responsibility from May to October: one or 2 in May, one or two in June, two to four in July, two or three in August, two or three in September, and two or three in October.

During these months, Solis said there will be cyclones that may “recurve,” or may not directly affect the Philippines, while others may make “landfall” or cross the country.

She emphasized that the first few months of the southwest monsoon season, from May to July, are typically when recurving cyclones occur.

However, Solis said a recurving cyclone could strengthen the effects of the habagat by pulling the moisture causing rains.

On May 2, PAGASA raised the El Niño Southern Oscillation Alert and Warning System to “alert” as the probability of El Niño developing in the June-July-August period increased to 80 percent.