The Philippines’ weather bureau on Friday, October 15, declared the start of La Niña and the end of the southwest monsoon or hanging habagat.
La Niña, which will lead to more rain, is expected to last until the first quarter of 2022.
“La Niña is usually associated with above normal rainfall conditions across most areas of the country during the last quarter of the year and early months of the following year,” the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) said in a statement.
“Rainfall forecast from October 2021 to March 2022 suggests that most parts of the country will likely receive near to above normal rainfall conditions.”
PAGASA said the declaration of La Niña was based on the cooling of sea surface temperatures in the central and equatorial Pacific, which has been recorded since July.
In a separate statement, PAGASA also announced the termination of the southwest monsoon, noting that it has “significantly weakened” over the past few days.
In addition, the weather bureau observed the “strengthening of the high pressure area over mainland Asia” and projected a “northeasterly surge over Northern Luzon within the next five days.”
“This means that the season in the Philippines is now in the process of transition, which will lead to the gradual onset and progression of the northeast monsoon in the coming weeks,” PAGASA said.
The northeast monsoon or hanging amihan, which typically lasts from October until February or March, will bring cool, dry air to the country.
The ongoing La Niña, however, could enhance the northeast monsoon, which might cause floods and landslides.
Prepare for more rain
Tropical cyclones may dump rain and further enhance the northeast monsoon, too.
PAGASA expects four to six tropical cyclones to enter or develop within the Philippine Area of Responsibility during the period of La Niña. Most of these tropical cyclones are seen to make landfall.
The weather bureau warned that the eastern parts of the country, “which normally receive greater amount of rainfall at this time of the year,” may be most affected by the hazards.
PAGASA urged government agencies, local government units, and the public to take precautionary measures.
“Kailangan paghandaan po natin ‘yung mga areas na vulnerable sa mga pagbaha (There should be preparations for areas which are vulnerable to floods),” PAGASA Deputy Administrator for Research and Development Esperanza Cayanan said in a briefing.
“[Dapat] alam na ng mga kababayan natin kung saan sila lilikas o kung paano lilikas…. Nakahanda ang lahat (The people should know when to evacuate and how to evacuate. Everyone must be prepared).”
Aside from tropical cyclones and the northeast monsoon, there could also be low pressure areas, the intertropical convergence zone, the tail-end of a frontal system, easterlies, and thunderstorms from October 2021 to March 2022.
PAGASA said the previous La Niña episode in 2020-2021 was weak to moderate. The last strong La Niña was experienced in 2010-2011. – Rappler.com