Tropical depression Agaton’s slow movement over the Philippines was a major contributor to its extreme rainfall and the resulting flooding in several parts of southern Luzon, Visayas, and Mindanao.

But why did the tropical cyclone behave this way?

Weather specialists of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) explained why tropical depression Agaton (international name: “Megi”) stalled over the country for several days.

Obet Badrina and Chris Perez attributed the slow movement of Agaton to the cyclone’s weak steering environment.

“Walang nagpapatakbo sa kanya or yung tinatawag na steering . Normally, may high pressure area na nagpapatakbo sa bagyo, sa case ni Agaton wala (No one is driving it or the so-called steering force. Normally, there is a high pressure area that runs the cyclone, in Agaton’s case, there is none),” Badrina said.

Perez further explained: “Nasa weak steering environment ang bagyong Agaton, dagdag pa diyan yung presence ng dalawa pang weather systems west and east ng bagyo—LPA near Palawan and bagyo outside PAR (Typhoon Agaton is in a weak steering environment, in addition to that is the presence of two other weather systems west and east of the typhoon—the LPA near Palawan and typhoon outside PAR).”

The LPA west of the Philippines has already dissipated while the typhoon, with the international name “Malakas,” east of the country has left the country’s area of responsibility after its brief entry on April 12.

PAGASA gave it a local name “Basyang” while inside the Philippine area of responsibility.

Perez also noted that Agaton’s slow movement can happen at any moment.

“Yung halos hindi pagkilos ng mga bagyo ay pwedeng mangyari anytime. Mas madalas lamang na ang mga bagyong namo-monitor natin ay mas defined ang pagkilos throughout its duration (The almost stationary movement of cyclones can happen anytime. It is just that more often than not, the cyclones we monitor have more defined action throughout its duration),” he explained.

Badrina also pointed out that the occurrence of tropical cyclones at this time of the year is not a rare occurrence.

“Hindi naman (unusual ang bagyo at this time of the year) kasi may instances naman na nagkabagyo tayo during April (It’s not that unusual that a tropical cyclone occurs at this time of the year because there are instances that we had a cyclone during April),” Badrina said.

He also pointed out that the occurrence of a tropical cyclone this month could be attributed to the prevailing La Niña.

After lingering over the country in the past few days, Agaton fizzled into a low pressure area on Tuesday evening, April 12.

PAGASA weather specialist Benison Estareja said, the LPA, formerly Agaton, is expected to become just a trough or extension of Malakas in the next few hours.