MANILA, Philippines – The shear line and the trough or extension of a low pressure area (LPA) inside the Philippine Area of Responsibility (PAR) are bringing rain to parts of the country on Halloween, Tuesday, October 31.

The shear line is the point where cold air from the northeast monsoon or amihan converges with warm air from the Pacific Ocean.

The LPA, meanwhile, was located 470 kilometers east of Virac, Catanduanes, as of early Tuesday. It only has a slim chance of developing into a tropical cyclone.

Scattered rain showers and thunderstorms are expected in the following areas on Tuesday due to the shear line and the trough of the LPA:

• Visayas
• Bicol
• Mimaropa
• Quezon
• Aurora

The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) warned of possible flash floods and landslides in the affected areas.

The northeast monsoon will also cause light rain in Northern Luzon and Central Luzon on Tuesday, but PAGASA sees “no significant impact.”

The rest of the country, including Metro Manila, will have generally fair weather with just localized thunderstorms.

No tropical cyclones have entered or formed inside PAR in October. The monthly average for October, from 1948 to 2022, is 2.6.

For the next six months, or from November 2023 to April 2024, PAGASA estimated there may only be two to five tropical cyclones.

El Niño, which triggers below-normal rainfall conditions in the Philippines, persists in the tropical Pacific. It is currently considered moderate but may become strong in the coming months. – Rappler.com