Why the Philippines is Being Battered By Yet Another Fearsome Typhoon
Koppu made landfall early Sunday morning local time as a strong category 3 with winds nearing 124 miles (200 kilometers) per hour. The storm, known as Lando in the Philippines, toppled trees and buildings, killing a 14-year-old boy and a 62-year-old woman. Torrential rains have flooded entire towns and displaced tens of thousands of people.
Evaporation of warm water fuels these disastrous storms, which are alternately known as hurricanes, typhoons, and cyclones. Water temperatures around the Philippines regularly top 82°F (28°C), which is the temperature that typhoons need to get going.
The Philippines sits in what scientists call the “warm pool” in the Western Pacific, with nothing between the country and open water.
Those warm sea surface temperatures mean more water evaporating into the atmosphere, loading a hurricane with more energy, said Kerry Emanuel, an atmospheric scientist at MIT in an earlier interview.
Forecasters predict the storm will stick around until Wednesday of this week before turning north towards Taiwan.
What Makes Koppu Special
The fact that Koppu is such a slow storm means it has more time to power up. The typhoon will lose steam once it’s separated from warm water, although forecasters expect Koppu to intensify again as it reemerges over the ocean north of the Philippines later this week.
All that atmospheric churning translates to turmoil in the ocean. Typhoons drag up cold seawater, which can put a damper on things. “A lot of hurricanes don’t get as strong as they could because of this,” Emanuel said.
Another component that can put a stop to these fierce storms is wind shear. Those upper atmospheric winds bring drier air into the center of a hurricane, which is “like throwing cold water on a fire,” said Emanuel. “It just throttles the whole engine back.”
That’s why Koppu didn’t strengthen until recently. Wind shear kept the storm from reaching its full potential early in its formation.
Wind Isn’t The Whole Story
While hurricanes are categorized based on their wind speeds, wind isn’t typically the most dangerous part of such storms. “It’s the storm surge,” said the atmospheric scientist—that bulge of water built up in front of a cyclone or hurricane courtesy of its winds.
It’s the number one killer in hurricanes, Emanuel said. “That’s what killed people in Katrina; it’s what killed people in Sandy and in Haiyan.”
Sandy’s storm surge flooded New York City’s subway system and runways at the city’s airports while damaging New Jersey’s transportation system. In total, the storm surge caused $400 million in damage.
Super typhoon Haiyan—the strongest typhoon on record to hit land—sent a wall of water nearly 25 feet (7.5 meters) high onto the Philippine Island of Leyte in November 2013. The storm surge ripped apart buildings and washed away entire towns. (Learn why this monster storm was so unusual.)
Emanuel likened a storm surge to a tsunami. One just happens to be caused by earthquakes (tsunamis), while the other is generated by hurricanes.
Flash flooding caused by intense rains is also a major killer, Emanuel said. “Hurricane Mitch in 1998 killed 12,000 people, and it was all from flash flooding.”
Forecasters are predicting up to 40 inches (102 centimeters) of rain in some parts of the Philippines. The flooding has gotten so bad that rescuers have been unable to reach towns and villages in need. The fear now is that because the ground is so saturated with water entire hillsides could collapse.
The worrisome thing though, is that climate change will likely increase the frequency of “the high-end hurricanes,” Emanuel said. Those categorized as threes or above (the scale tops out at five).
And those powerful storms have the potential to produce a lot of rain, flooding, and strong storm surges.
Super typhoon Koppu is the northern hemisphere’s 19th category four or five tropical cyclone. The storm has set the record for the most such storms in one year. The previous record was 18 in 2004.