The effect of the shear line has slightly weakened, affecting fewer areas over the next 24 hours, said the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) on Tuesday, Dec. 3.
PAGASA Weather Specialist Patrick Del Mundo explained that the shear line is where warm air from the Pacific Ocean (easterlies) meets the cold air from the northeast monsoon (amihan), causing rainfall.
This weather system is expected to bring heavy to intense rainfall—ranging from 100 to 200 millimeters—to Isabela, and moderate to heavy rainfall—ranging from 50 to 100 millimeters—to Cagayan and Aurora on Tuesday.
By Wednesday, Dec. 2, Cagayan may experience heavy to intense rainfall, while Isabela is likely to see moderate to heavy precipitation.
The shear line may also bring cloudy skies, scattered rains, and isolated thunderstorms to Metro Manila, Cagayan, Isabela, Quirino, Aurora, Nueva Ecija, Bulacan, Rizal, Quezon, and Kalayaan Islands over the next 24 hours.
Meanwhile, Del Mundo said the amihan will continue to bring cooler weather, with cloudy skies and rainy conditions over the rest of Cagayan Valley and Cordillera Administrative Region.
PAGASA warned of flash floods or landslides that may occur, particularly during moderate to heavy rainfall in areas affected by the shear line and amihan.
It added that the impact of amihan is expected to remain minimal in Ilocos Region, where only isolated light rains are anticipated.
Meanwhile, the rest of the country may experience isolated rain showers due to localized thunderstorms. The public is advised to remain vigilant for possible flash floods or landslides during severe thunderstorms.