intertropical convergence zone

BY KIRSON L. CASTAÑOS/DSSC Intern

THE DEPARTMENT of Science and Technology–Philippine Atmospheric, Geophysical and Astronomical Services Administration (DOST-PAGASA) held a learning session and weather update on Friday, July 3, as part of National Disaster Resilience Month.

Engr. Alan Ray C. Ribo, PAGASA weather specialist, opened by distinguishing weather—short-term atmospheric conditions that can shift within minutes or hours—from climate, the long-term pattern of atmospheric behavior over seasons or years.

Ribo reported that the tropical depression earlier monitored has already exited the Philippine area of responsibility, while Typhoon Henry’s threat potential likewise moved out of PAR as of July 2. 

However, a new tropical cyclone-like vortex (TCLV 1) is expected to form east of Luzon around July 9, possibly tracking toward Northern Luzon, with a second system, TCLV 2, expected to follow and affect the extreme northern part of the island. 

Numerical weather models indicate a tropical cyclone may enter the area by July 7 at roughly five kilometers altitude, with strong intensity and a possibility of recurving due to interaction with a high-pressure area.

Ribo noted that thunderstorm occurrences peak in May and October, with up to 16 days of thunderstorm activity recorded in those months. For Davao City, rainfall traditionally normalizes in June and October, with the monsoon expected to ease in July—though PAGASA continues to monitor the transition period for possible thunderstorms and flooding.

The public was encouraged to check PAGASA’s climate data for Davao City, which shows April as the hottest month, with thunderstorm and lightning activity most likely from May to July. Ribo also outlined the country’s four climate types: Type 1 (Luzon/Quezon City area) with heavy monsoon rainfall; Type 2 (Caraga region) with rains concentrated from December to February during Amihan; Type 3 (Zamboanga Peninsula) with lighter monsoon rains; and Type 4 (Davao Region), where rainfall—around 100 millimeters, compared to Caraga’s 1,000 millimeters—is evenly distributed year-round regardless of monsoon season.

On El Niño, Ribo confirmed the phenomenon was officially declared in June 2026, with drought already affecting parts of Luzon, while Mindanao remains partly buffered by southwest monsoon rainfall reserves. 

Oceanic data from May 24 to June 20 showed sea surface temperatures above average in the central-to-eastern Pacific, with anomalies of 0.5 to 1.5°C, alongside enhanced convection over southeastern Mindanao but suppressed rainfall elsewhere in the country.

Forecasters project more than 90% probability of El Niño conditions through July, rising to 100% from August to October, and persisting with high probability into early 2027. A strong El Niño is favored for the August-October period (69%), with a very strong event favored from October to January (62%), per PAGASA’s June 24 update. 

Davao City, Sarangani, and Tawi-Tawi could see two to three consecutive months of below-normal rainfall, though Davao remains in “normal” status for now due to the southwest monsoon. Ribo urged continued vigilance through November.

The session also covered hydrometeorological hazards, including the Amihan season’s cool, dry northeast winds (November to May), the formation of shear lines when opposing wind systems meet, and the Intertropical Convergence Zone (ITCZ), which can bring rainfall to the Visayas and Mindanao and contribute to low-pressure development. PAGASA’s Mindanao Regional Services Division assured the public that all systems remain under close monitoring.

Photo Courtesy PIA Davao Region/Facebook