Does the Sierra Madre mountain range weaken the storms? Experts explain 

The Sierra Madre mountain range has made the headlines anew following the onslaught of Severe Tropical Storm Uwan, which intensified into a super typhoon. 

Many believe that the mountain range helped weaken the storm. According to Chino Gaston’s report on “24 Oras” on Tuesday, the state weather bureau PAGASA said that what truly weakens a typhoon is its landfall.

“Regarding sa structure ng bagyo, kung saan na napapansin ng iba, buong-buo yung mata niya sa may Philippine Sea. Pero pagtama dito sa kalupaan ng Sierra Madre, nabasag yung kanyang sirkulasyon. Definitely may effect din yung matataas na mga lugar, mountainous areas ng Sierra Madre, Caraballo and Cordillera mountain regions, dito po sa structure o itsura ng isang bagyo. Kaya madalas di na natin nakikita yung sentro or ikot or mata ng bagyo pag dumaan na ito sa kalupaan,” said PAGASA weather specialist Benison Estareja. 

(Regarding the structure of the typhoon, some notice its eyewall is completely intact over the Philippine Sea. But when it hits the landmass of the Sierra Madre, its circulation is broken. Definitely, the high areas, the mountainous areas of the Sierra Madre, Caraballo, and Cordillera mountain regions, also have an effect here on the structure or appearance of a typhoon. That’s why we often no longer see the center or the eye of the typhoon once it passes over land.) 

Atmospheric scientists at the University of the Philippines conducted a simulation that found that the presence or absence of mountains on Luzon made little difference. This is because typhoons primarily gain strength over the ocean by drawing energy from evaporating water.

“We simulated 40 plus na bagyo na dumaan sa Luzon. So, ginawa namin is, doon sa isang simulation, nandyan si Sierra Madre. Another simulation, flinaten namin si Sierra Madre. So ang tanong ngayon ay kung malakas yung effect ni Sierra Madre, so ibig sabihin, dun sa flattened, hindi gaanong hihina yung bagyo. Dun sa nandyan si Sierra Madre, hihina yung bagyo. And it turns out na medyo same lang yung paghina ng bagyo,” said UP-IESM Atmospheric Physics Laboratory head Gerry Bagtasa. 

(We simulated 40 plus typhoons that passed through Luzon. So, what we did was, in one simulation, the Sierra Madre was present. In another simulation, we flattened the Sierra Madre. So, the question now is whether the effect of the Sierra Madre is strong. If it is, then in the flattened version, the typhoon won't weaken much. In the version where the Sierra Madre is present, the typhoon will weaken. And it turns out that the weakening of the typhoon was almost the same.) 

While the mountain range may not significantly impact a typhoon's overall weakening, its presence is crucial for absorbing the massive rainfall that typhoons bring, provided its forests remain intact.

The Save Sierra Madre Network Alliance warns that extensive deforestation increases the risk of landslides and allows rainwater to flow unchecked, directly contributing to severe flooding in low-lying areas.

Although it appreciates the attention brought by social media memes and content highlighting the Sierra Madre's importance, the group urged that concrete action be taken to protect the mountains, beyond just online engagement.

“Kalat-kalat ang iba't ibang quarry companies, nickel mining companies. Actually doon sa Nueva Vizcaya meron nakakuhang permit na isang mining corp…At the same way yung pagtatayo ng Kaliwa Dam na malawakang tinututulan ito ng mga partners naming katutubo,” said Save Sierra Madre Network Alliance vice chairperson Adrian Romero. 

(Various quarry companies are scattered around, nickel mining companies actually—there in Nueva Vizcaya, one mining corporation got a permit…And at the same time, the construction of the Kaliwa Dam is being widely opposed by our indigenous partners.) 

“Gusto namin sa organization na magtranslate yung creativity sa social media into warm bodies na mag-lobby sa DENR na community organizing, nagsasama-sama para mag tree planting tingin ko ‘yan ang challenge sa maraming mga netizens,” he added. 

(We in the organization want the creativity on social media to translate into warm bodies that will lobby the DENR for community organizing, gathering together for tree planting. I think that is the challenge for many netizens.) 

Data gathered by the GMA News Research showed that the more than 1.8 million hectares of forest in Sierra Madre in 2003 were already reduced by over 130,000 hectares, leaving only 1.693 million hectares, based on the survey in 2020.

If such a trend continues, the forest cover of Sierra Madre may be further reduced by half by 2031. 

GMA Integrated News is reaching out to the Department of Environment and Natural Resources for a comment. —Vince Angelo Ferreras/LDF, GMA Integrated News