The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Friday, Oct. 15, said the La Niña has developed and will likely impact the country's weather conditions until the first quarter of 2022.
"Recent oceanic and atmospheric conditions indicate La Niña has developed in the tropical Pacific," PAGASA Deputy Administrator Esperanza Cayanan said in a virtual press briefing.
La Niña, which is characterized by unusually cool ocean surface temperatures in the Central and Eastern Equatorial Pacific, 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.
What does this mean for PH?
Based on the PAGASA's rainfall forecast, Cayanan said that most parts of the country will likely receive near to above-normal rainfall conditions from October 2021 to March 2022.
"In addition, four to six tropical cyclones, most of which are landfalling tropical cyclones, are expected to enter or develop in the Philippine area of responsibility," she pointed out.
PAGASA's Climate Monitoring and Prediction Section chief Ana Liza also noted that cyclones occurring towards the end of the year are mostly "landfalling, crossing, and possibly disastrous" cyclones.
From the past La Niña events, adverse impacts such as floods and landslides occurred during the northeast monsoon or "amihan" season, she added.
Cayanan said that tropical cyclones enhancing the northeast monsoon could trigger floods, flash floods, and rain-induced landslides in areas that are susceptible to these hazards.
She pointed out that areas in the eastern sections of the country, which normally receive a greater amount of rainfall at this time of the year, are most at risk of the impacts of the La Niña.
"Adverse impacts are likely over the vulnerable areas and sectors of the country," she said.
She advised the public to take precautionary measures to mitigate the potential impacts of the La Niña event.
In November 2020, the prevalence of La Niña contributed to the formation of more destructive tropical cyclones, such as typhoons Rolly and Ulysses.
Also in previous years, Cayanan pointed out that excessive rainfall linked to the La Niña caused the Guinsaugon landslide in Southern Leyte in February 2006 and massive flooding in Mindanao in January 2009.
Back-to-back La Niña
The current La Niña occurs back-to-back with the just-concluded La Niña event in October 2020-June 2021.
Solis said that back-to-back La Niña episodes are not unusual, noting that the last six episodes occurred back-to-back.
These were in 2007-2008 and 2008-2009; 2010-2011 and 2011-2012; and 2016-2017 and 2017-2018.