Scattered rains and isolated thunderstorms are expected in Metro Manila on Thursday due to the shear line, while the intertropical convergence zone (ITCZ) is seen to affect Southern Luzon, the Visayas, and Mindanao, according to the state weather bureau.
Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) weather specialist Chenel Dominguez explained in a public forecast that a shear line forms when warm and cold air masses converge.
‘For today’s weather in Luzon, we expect scattered rains caused by the shear line, or the convergence of warm and cold air, which will bring scattered rains over Isabela, Aurora, Calabarzon, and Metro Manila,’ Dominguez said in Filipino.
‘Meanwhile, the intertropical convergence zone or ITCZ will also bring a high chance of scattered rains over the Bicol Region and Mimaropa,’ she added.
The ITCZ is a global band near the equator where trade winds from both hemispheres meet. Like the shear line, it can also trigger rainfall.
Aside from these two weather systems, Dominguez said the northeast monsoon, locally known as amihan, is expected to bring cloudy skies with rains over Batanes, Cagayan, Apayao, and Ilocos Norte.
The rest of the country may experience generally fair weather, but localized thunderstorms remain possible.
‘In the rest of Luzon, in areas I have not mentioned, we expect generally fair weather but also a high chance of short-lived rains due to localized thunderstorms, especially in the afternoon and evening,’ she said in Filipino.
LPA monitoring
While there is no active low-pressure area inside the Philippine area of responsibility (PAR) at present, Dominguez said Pagasa is monitoring one outside the country’s boundary.
Dominguez said the LPA was last spotted 1,515 kilometers east of northeastern Mindanao. While it remains less likely to become a tropical cyclone within the next 24 hours, the likelihood of it becoming a full-fledged cyclone is ‘expected to increase’ in the coming days.
She said it is expected to enter PAR by Sunday or Monday, adding that they are looking at two possible scenarios for it.
The first scenario shows the LPA moving northwestward and staying almost stationary over the Philippine Sea due to its interaction with a stationary front, possibly making landfall in Northern Luzon by Sunday, Nov. 9.
The second scenario indicates a slightly faster movement, with a potential landfall over Eastern Visayas by Nov. 4.
However, Dominguez stressed that these remain projections as the LPA is still far from the Philippine boundary.
‘As of now, the LPA is still far from the country, so many changes in its track are still possible,’ she said in Filipino.