The early Monday morning intense rains that showered Puerto Princesa and some Palawan towns were brought by the Intertropical Convergence Zone (ITCZ), the local state weather bureau explained.
Local weather chief Sonny Pajarilla of the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) said that the amount of rainfall recorded on Monday reached 20.4 millimeters (mm) from 2:30 to 7:00 in the morning.
The rain showers are classified under the intense category if about 17.5 mm is recorded within an hour. The heavy rain showers on Monday morning were observed from 3:00 to 3:50 am at 18mm.
“Kapag ITCZ ay may mga pag-ulan tayo, iyon ang rason kaya makapal ang ating ulap. Hindi lang ‘yan dito sa Palawan kung hindi sa buong MIMAROPA area. Hindi lang sa atin may malakas na pag-ulan, kasama na may malakas na pag-ulan kahit dito sa Iloilo, Cagayancillo, iyon ang rason, moving ‘yan. Sumisikat ang araw pero may ibang bahagi ng Palawan na tinatamaan pa rin ng ulap,” he said.
“Nangyayari ang ITCZ dahil tayo ay tropical country kung tawagin, nasa tropics tayo, lagi tayong naiinitan, laging may araw. From the northern hemisphere of winter ay umangat na uli ang ating araw, papunta na ‘yan kaya nagta-transition tayo from northeast monsoon to southwest. Transition period natin, nandyan ‘yong pagpasok ng easterly winds, ridge of a high pressure at ‘yong ITCZ,” he added.
The existing ITCZ affects Visayas, Mindanao, and Southern Luzon where Palawan is included.
During ITCZ, Pajarilla explained that there is the convergence of winds from the southern and northern hemispheres.
“Every time na may convergence, ang net force niyan is vertical. Ang nagiging resultant niyan ay paangat o paakyat ng atmosphere. Kasi ang atmosphere natin ay dependent lang sa movement, ‘yong ating upper level ng atmosphere, walang sariling characteristic. Nakadepende lang ‘yon sa transport sa kaniya ng ating molecules.
The vertical motion is needed to transport the surface atmospheric moisture to the upper level of the atmosphere, this results in cloud development whenever there is a convergence, he said.
There are different convergences such as the low-pressure area, frontal system, and ITCZ.
Mostly cloudy skies with rain showers will be observed throughout the week due to the ITCZ, he said.