The Philippines may have one or two more tropical cyclones in December amid the prevailing threat of La Niña across the country, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) said during its climate outlook forum on Wednesday, Nov. 24.
PAGASA's Climate Monitoring and Prediction Section chief Ana Liza Solis said the number of the tropical cyclone was estimated based on the climatological record from 1948 to 2010.
She pointed out that tropical cyclones that form in December usually make landfall or cross Visayas or Mindanao, while some "recurve" and do not hit the Philippine landmass.
However, even without a tropical cyclone, Solis said that rain-bearing weather systems enhanced by La Niña still increase the risk of flooding or landslides, especially in areas vulnerable to these hazards.
Some of the rain-bearing weather systems include the intertropical convergence zone or ITCZ, low pressure areas, tropical cyclones, northeast monsoon or amihan, and the shear line or tail-end of the frontal system.
Solis said there is an 80 percent chance that the La Niña weather pattern will persist until the first quarter of 2022, which means the likelihood of having above-normal rainfall conditions across most areas of the country is still high.
"La Niña is likely to continue through January-February-March 2021 and returning to ENSO-neutral by March-April-May season," Solis said.
Based on the PAGASA's rainfall forecast for December, Solis noted that generally near-normal to above-normal rainfall conditions may persist, "but mostly above normal in NCR , IV-A, IV-B, Bicol region, and mainly in the Visayas region."
There is, however, a slim chance of tropical cyclone development from January to March.
By January 2022, "generally near to above normal over most parts of the country, except some below to near normal rainfall conditions over CAR , Region I, and Region III," Solis said.
By February 2022, rainfall will likely be below to near normal in CAR, Regions I, III, III, and NCR, while the rest of the country will receive near to above normal rainfall conditions.
By March 2022, most parts of the country will have generally above normal rainfall conditions, except for CAR where below to near normal rainfall conditions are more likely.