Experts: Sierra Madre can cushion impact but can’t fully stop typhoon

National

THE Sierra Madre may help soften a typhoon’s blow, but it cannot stop one.

This was the reminder from scientists and weather experts on Monday, Nov. 10, as Filipinos once again credited the Sierra Madre for helping weaken Typhoon Uwan (international name Fung-wong), which made landfall over northern Luzon over the weekend before moving toward the West Philippine Sea.

According to the Department of Science and Technology (DOST), the Sierra Madre Mountain Range indeed plays a crucial role in slowing down or weakening the winds of tropical cyclones that hit Luzon, especially on its northeastern side.

However, it does not provide complete protection from their destructive effects.

“Maaaring sabihing nakatutulong ang Sierra Madre bilang panangga sa mga bagyo sa Luzon sapagkat may kakayahan itong bahagyang pahinain o bagalan ang lakas ng hanging dala ng bagyo—lalo na sa hilagang-silangang bahagi ng rehiyon. Gayunman, hindi ito nagbibigay ng ganap na proteksyon laban sa matitinding epekto ng mga ito,” DOST said in a post on its official Facebook page.

A 2023 study by Dr. Gerry Bagtasa and Dr. Bernard Alan Racoma, published in the Philippine Journal of Science, offers the most comprehensive scientific look at the so-called “Sierra Madre shield.”

Using a numerical weather prediction model, the researchers simulated the impact of the Sierra Madre and Cordillera Mountain Range on 45 typhoons that struck Luzon between 2000 and 2020.

Mountains weaken winds, but not right away

Their findings show that typhoons do not significantly weaken during the first six hours after landfall, even when crossing mountain ranges.

The Cordillera Range has a stronger effect on wind reduction than the Sierra Madre, while the latter mainly influences rainfall patterns.

The study noted that the Sierra Madre reduces rainfall on its western side, including Metro Manila, by 23 to 55 percent, while helping to weaken both wind and rain in the Cagayan Valley region.

Typhoon Uwan weakens after landfall

Uwan, which earlier reached super typhoon category, weakened after interacting with Luzon’s rugged terrain, including the Sierra Madre.

As of 1 a.m. Monday, the typhoon’s center was located in Bagulin, La Union, packing maximum sustained winds of 165 kilometers per hour (kph) and gusts of up to 275 kph, according to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa).

Pagasa weather specialist Obet Badrina said Uwan’s movement was “fast” at 30 kph toward the west-northwest, noting that it was likely to exit Luzon’s landmass by Monday morning.

“If you notice, the gustiness is a bit strong as it hits the terrain or the mountains of northern Luzon,” Badrina said. “Possibly, in our next 5:00 a.m. update, Uwan will already be in the West Philippine Sea.”

He added that the typhoon is now mainly affecting northern and central Luzon, with significantly less rainfall expected in Southern Luzon, Visayas, and Mindanao.

Pagasa has since lifted the highest wind signal, No. 5, in several areas following the storm’s weakening.

Calls to protect Sierra Madre rise anew

Following Uwan’s landfall, social media was flooded with renewed calls to protect the Sierra Madre, Cordillera, and Caraballo ranges from deforestation, illegal logging, and mining.

Environmental groups and citizens alike echoed the call to preserve these landforms, which serve as natural barriers and critical ecosystems.

The Climate Change Commission earlier described the Sierra Madre as Luzon’s “natural fortress” and the country’s first line of defense against climate-induced disasters—a role now compromised by forest degradation.

The Sierra Madre, stretching 540 kilometers from Cagayan to Quezon, also functions as a vital carbon sink, absorbing carbon dioxide and helping stabilize weather patterns. It hosts over 3,500 plant species, 58 percent of which are endemic to the Philippines.

Presidential Proclamation No. 413 designates September 26 as “Save Sierra Madre Day” to promote awareness and conservation of the mountain range.

Expert clarification

American storm chaser Josh Morgerman, who is currently in the Philippines documenting Uwan, also weighed in on social media to correct misconceptions.

“Many folks are posting misinformation about the Sierra Madre Mountains in the Philippines,” Morgerman wrote. “Let me set the record straight: the Sierra Madre chain weakens typhoons after they make landfall on the east coast of Luzon. These mountains do not protect the east coast of Luzon, which regularly experiences some of the strongest tropical cyclone impacts in the world.”