UP study finds storm patterns in PH that can guide response
A new study has found that storms which made landfall in the northern part of the Philippines tend to be stronger but slower moving, while those that affected the country’s southern portion are typically faster and accelerate more rapidly.
This pattern in a storm’s speed and movement has implications on the type of hazards it may bring to a certain area and the response needed to protect communities, according to a study by Bernard Alan Racoma and Gerry Bagtasa from the University of the Philippines (UP) Diliman.
In their article, “Characteristics and Near-Landfall Behavior of Tropical Cyclones Affecting the Philippines,” published online in November, Racoma and Bagtasa from the Institute of Environmental Science and Meteorology of the UP College of Science examined 372 tropical cyclones that made landfall in the country from 1979 to 2024.
Geographic implications
They found that a storm’s behavior when making landfall is related to its geographic location, noting that tropical cyclones in the southern section of the country tend to approach more rapidly and show higher acceleration.
This means communities in the Visayas and Mindanao have less time to prepare for a typhoon because it typically arrives in the area much faster. Forecast tracking, timing and downstream messaging also become more complicated due to the acceleration or the sudden shift in the storm’s movement, the study pointed out.
On the other hand, storms in the northern part of the country typically decelerate or slow down before or during landfall, resulting in the tropical cyclone having a longer interaction with the land which increases the risk of sustained rainfall and localized flooding.
Previous studies have also shown that slower-moving storms tend to produce heavier rainfall regardless of intensity. Communities in Luzon, therefore, become exposed to threats of prolonged flooding and landslides due to this kind of behavior.
Shorter interaction
On top of this, the study also found that although tropical cyclones often stay inside the Philippine area of responsibility (PAR) for several days, its interaction with the country’s landmass typically lasts just around 21 hours.
Racoma explained that “in terms of geometry, the Philippines is a little slender. The country is longer from north to south compared to east to west. Since tropical cyclones usually move from east to west, they tend to cross this shorter path faster.”
“Another possible explanation is because of the loss of the fuel source—the warm ocean. Tropical cyclones draw their energy from the sea, and they typically don’t like staying over land,” he added.
However, the study stressed that storms can still pose a threat even if it has yet to make landfall in the country. Tropical cyclones that pass through eastern or northern Luzon, it noted, can enhance the southwest monsoon (“habagat”) and bring rainfall over the western seaboard.
Rapid intensification
Moreover, it noted that tropical cyclones that rapidly intensify tend to begin their intensification as early as 36 hours before landfall, with peak intensification commonly occurring while a storm is already within PAR.
“Rapid intensification occurs very fast—typically within 24 hours. We don’t yet fully understand it; even weak storms can intensify quickly. We should avoid waiting for a storm to intensify before preparing. Half of tropical cyclones that form or enter the PAR make landfall, and usually rapid intensification occurs within this region,” said Racoma.
To improve disaster preparedness, the scientists called on communities to monitor when tropical cyclones enter or form within the PAR, and also urged them to treat all developing storms seriously.
The study also emphasized that when it comes to disaster preparedness, the public should take into account not just the number of storms that may arrive, but its strength, speed and how quickly its conditions could change.
Strongest
The Philippines is one of the most typhoon-prone countries with an average of 20 typhoons entering its area each year, and at least eight making landfall.
Last year, there were 22 typhoons that hit the country, with Typhoon “Uwan” (international name: Fung-wong) that hit in early November considered the strongest.
Uwan affected about 5 million people and affected 16 out of 18 regions due to its wide diameter of 1,800 kilometers.
The last storm to affect the country last year was Typhoon “Verbena” (international name: Koto). It exited the Philippine area of responsibility on Nov. 27.
December, usually a busy month due to the Christmas and New Year celebrations, was storm-free.
