La Niña comes to an end as PH prepares for rainy season

Published May 29, 2021, 3:27 PM

by Ellalyn De Vera-Ruiz

The La Nña event that brought “above-normal” rainfall over the country in late 2020 to early 2021 is officially over.

Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) Climate Monitoring and Prediction Section chief Ana Liza Solis said that La Niña has returned to El Niño–Southern Oscillation (ENSO)-neutral conditions, where there is neither a La Niña nor El Niño that persists.

“ENSO-neutral condition [is] likely to continue through June-August 2021 season (67 percent chance),” Solis said during PAGASA’s climate outlook forum on Wednesday, May 26.

Photo taken during the onslaught of Typhoon “Ulysses” in November 2020 (JANSEN ROMERO / MANILA BULLETIN)

PAGASA had announced the onset of La Niña in October 2020.

Tropical cyclones started to become active from October to November 2020 with the formation of eight cyclones in a row, seven of which made landfall over Luzon.

Except for tropical storm “Nika” (Nangka), seven cyclones–tropical depression “Ofel,” typhoon “Pepito” (Saudel), typhoon “Quinta” (Molave), super typhoon “Rolly” (Goni), severe tropical storm “Siony” (Atsani), tropical storm “Tonyo” (Etau), and typhoon “Ulysses” (Vamco) all traversed Luzon.

At the end of October, PAGASA said 92 percent of the country received above-normal rainfall, with “many areas (that) had received more than 200 percent of the normal rainfall.”

In the early months of 2021, above-normal rainfall has shifted to the Visayas and Mindanao.

The presence of La Niña is known to increase the potential of having extreme rainfall events caused by rain-bearing weather systems, such as northeast monsoon or “amihan,” tail-end of cold front, intertropical convergence zone, low pressure areas, and tropical cyclones.

As La Niña officially comes to an end, the rainy season in the country is expected to begin by the end of May or the first half of June.

“[The] onset of the rainy season associated with the southwest monsoon for Climate Type I areas is expected to commence soon,” Solis said.

Climate Type I areas have two pronounced seasons–dry from November to April and wet during the rest of the year. The period of maximum rain in these areas also coincides with the peak of the southwest monsoon or “habagat” from July to September.

PAGASA said that one to three tropical cyclones may enter or develop inside the Philippine area of responsibility in June.

Rainfall forecast from June to August shows that the country will have generally near normal rainfall conditions except for patches of below normal rainfall in Luzon.