The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) issued a warning on Friday, Nov. 15 about the potential risks of landslides and flash floods as Typhoon “Pepito” (international name: Man-yi) approaches rainfall-saturated areas in Luzon and Eastern Visayas.

In the PAGASA’s rainfall outlook issued at 11 a.m., intense to torrential rainfall (over 200 millimeters) is expected from Saturday noon to Sunday noon in Catanduanes, Albay, Sorsogon, and Northern Samar, which may lead to widespread flooding and landslides.

Heavy to intense rainfall (100 to 200 millimeters) may affect Eastern Samar, Camarines Sur, and Camarines Norte, where “numerous flooding events” are likely, especially in urbanized and low-lying areas or near rivers. Likewise, landslides are possible in areas with “moderate to high” susceptibility.

Moderate to heavy rainfall (50 to 100 millimeters) is likely in Masbate, Leyte, Quezon, Samar, and Biliran, where localized flooding and landslides are possible.

As Pepito moves over Luzon from Sunday noon to Monday noon, more areas are expected to experience intense totorrential rainfall, including Catanduanes, Quezon, Aurora, Camarines Norte, and Camarines Sur.

Heavy to intense rains may also affect Metro Manila, Northern Samar, Albay, Sorsogon, Marinduque, Cavite, Laguna, Rizal, Bulacan, and Nueva Ecija.

Bataan, Zambales, Tarlac, Batangas, Pampanga, Masbate, Romblon, Eastern Samar, Samar, Oriental Mindoro, Pangasinan, Nueva Vizcaya, and Quirino may experience moderate to heavy rains.

Saturated ground

In a press conference, PAGASA hydrologist Richard Orendain highlighted areas with critically high soil moisture levels, increasing the likelihood of hazardous weather conditions.

As of 8 a.m. on Friday, Orendain reported that soil moisture levels are dangerously high in several regions of Northern and Central Luzon, as well as parts of the Bicol Region.

“Fully saturated na ang mga lugar ng eastern Isabela and Cagayan area, extreme Northern Luzon, and Ilocos Region (The eastern portions of Isabela, Cagayan, extreme Northern Luzon, and the Ilocos Region are fully saturated),” he said. 

This means that even with moderate rainfall, there is a heightened risk of flooding and landslides in these areas.

One of the most concerning areas is Catanduanes, where soil moisture levels are between 65 and 90 percent. 

“Ibig sabihin, posible magkaroon ng landslides at floods sa lugar na ‘yan (This means that landslides and floods are possible in this area),” Orendain warned. 

In Catanduanes, rainfall of 85 to 110 millimeters, particularly in the northern and southern parts of the island, could result in flash floods and landslides, he said.

The mountainous terrain and the highly populated communities in these regions make them particularly vulnerable. 

He added that there are also areas in Quezon, Aurora, Albay, and Camarines Norte that are similarly at risk, as these are all within the typhoon’s path.

In Samar and Eastern Samar, soil saturation levels range from 65 percent to 85 percent, thus the likelihood of landslides and flooding in these areas is also high.

Orendain also pointed out the threat of flash floods, particularly in areas still recovering from Typhoon “Ofel” (international name: Usagi). 

“Katatapos lang ng bagyo na ‘yan kaya konting ulan lang about 45 millimeters of rainfall in six hours, posible ulit bahain itong lugar ng Isabela, Cagayan, extreme Northern Luzon, Ilocos Region (That typhoon just passed, and with just a small amount of rainfall, about 45 millimeters in six hours, it could flood again in areas like Isabela, Cagayan, extreme Northern Luzon, and Ilocos Region),” he said.

There are also areas in Metro Manila, Pampanga, Pangasinan, Tarlac, Camarines Norte, Quezon, and Aurora that are vulnerable to flash floods.

PAGASA Senior Weather Specialist Glaiza Escullar said the effects of Typhoon Pepito will be felt in Metro Manila starting Saturday, Nov. 16, through Sunday, Nov. 17.

On Saturday, the weather will be mostly cloudy, with localized rainfall expected, lasting one to two hours, accompanied by heavy downpours in Metro Manila.

Escullar added that Pepito is forecast to pass through the northern part of Metro Manila by Sunday, bringing intense rainfall to the area.

Flood advisories

In addition to the localized warnings, PAGASA has also issued general flood advisories for several regions, including the Cordillera Administrative Region (CAR), Ilocos Region, Cagayan Valley, Central Luzon, Calabarzon, Mimaropa, Bicol Region, and Eastern Visayas. 

These regions are at significant risk of flooding, and local authorities have been advised to take the necessary precautions to protect residents.

Orendain also advised residents in the affected areas to stay updated with weather forecasts and adhere to evacuation orders if necessary.