The Ceiling of Cyclonic Destruction—and Where Super Typhoon Haiyan Fits In

Satellite image of the record-setting tropical cyclone Haiyan that struck the Philippines in early November. Photo courtesy of NASA>

Category 5 Hurricane. Super Typhoon. Super Cyclonic Storm. Very Intense Tropical Cyclone. Category 5 Severe Tropical Cyclone. These are the special appellations for the rare and most intense classification of tropical cyclones, spiraling storms formed over the open ocean that are so big and coherent they can easily be identified from space.

The three-most common physical traits of a cyclone are wind speeds, internal pressure and storm surge. Other important characteristics include a storm’s size and forward speed. For the purpose of comparing storms, however, it is easiest to just focus on wind speeds.

The intensity of these storms is largely defined by their wind speeds. In other words, how fast can they twirl?

In the Atlantic and East Pacific Oceans, scientists have declared that storms must dance at least 158 miles per hour (mph) and keep, or sustain, the speedy pace for several minutes, possibly hours or even days to deserve the title. In the Northwest Pacific, North Indian, and Southwest Indian Oceans, there is a slightly lower bar of 150 mph. For storms brewing around Australia and in the greater South Pacific Ocean, meteorologists have set the upper threshold at around 142 mph.

Hundreds of tropical cyclones form each year, but only a handful of them reach the highest intensities. And when they do, such as last week when Super Typhoon Haiyan struck the Philippines, the world pays very close attention.

But Super Typhoon Haiyan, also called Yolanda in the Philippines, is not just any ol’ big storm—it is shaping up to be one of the biggest storms ever recorded and it holds the title for strongest storm to make landfall.

To better understand Haiyan in the context of storms within the Category 5 domain, I started culling the stats.

This year, only 2 other storms reached category 5 strength. Both eventually struck land, but at much lower intensities. Typhoon Usagi, also called Odette, formed in the Northwest Pacific, hit peak winds of 160 mph during its’ lifespan and made landfall as a Category 1. In the North Indian Ocean, Very Severe Cyclonic Storm Phailin was packing up to 160 mph winds. It struck India’s western coast as a major storm but not at full strength.

This year no hurricanes even reached “major” hurricane status, meaning a storm with winds of at least 111 mph or Category 3 status, in either the Atlantic or East Pacific Oceans.

Since 2000, there have been 62 storms of Category-5 intensity across the world. The amount of time these storms remained at Category 5 strength, ranged from less than 6 hours to around 2 days. Only 12 of them, or roughly 19 percent, went on to terrorize communities at top-strength:

Storm wind speeds can be measured in a bunch of different ways. For the purpose of this post, I am specifically referring to a category of wind measurements called “1-minute sustained winds.”

  1. (2001) Typhoon Bilis (also called Isang): Created in the Northwest Pacific Ocean and made a first strong landfall in Taiwan, followed by another devastating landfall in China. It boasted winds of approximately 160 mph.
  2. (2002) Very Intense Tropical Cyclone Hary: Spawned in the Southwest Indian Ocean and made landfall in Madagascar. Hary had peak winds of 160 mph.
  3. (2003) Typhoon Maemi (also called Pogi): Formed in the Northwest Pacific Ocean and made its first landfall at top strength in Japan. Maemi then went on to make a second landfall in South Korea. The storm’s maximum sustained winds were 175 mph.
  4. (2004) Typhoon Nida (also called Dindo): Generated in the Northwest Pacific Ocean, it made landfall in the Philippines at top intensity. At it’s most intense stage, Nida had sustained winds of 165 mph.
  5. (2004) Severe Tropical Cyclone Heta: Born in the South Pacific Ocean, the storm crossed the American Samoa archipelago at major strength. Heta had regular winds of up to 160 mph.
  6. (2005) Severe Tropical Cyclone Oaf: Spawned in the South Pacific Ocean, this major cyclone similarly hit the American Samoa islands. Oaf’s winds went up to 165 mph.
  7. (2005) Severe Tropical Cyclone Percy: Developed in the South Pacific Ocean and crossed several island nations. Percy’s maximum sustained winds went up to 160 mph.
  8. (2007) Hurricane Dean: Created in the Atlantic Ocean, Dean reached Cat 5 intensity twice in its lifespan and made landfall in Mexico at full-strength. The storm had sustained winds of up to 173 mph.
  9. (2007) Hurricane Felix: The same season as Dean, Felix formed in the Atlantic Ocean and similarly hit top strength two times. The storm made landfall in Nicaragua at peak intensity. It’s winds were also approximately 170 mph.
  10. (2010) Typhoon Megi (also called Juan): Born in the Northwest Pacific Ocean, this storm made an initial landfall in the Philippines. After weakening, it later crossed China. The maximum sustained winds were observed at a whopping 185 mph.
  11. (2012) Typhoon Bopha (also called Pablo): Generated in the Northwest Pacific Ocean, Bopha’s maximum sustained winds reached 175 mph and it made an initial strong landfall in the Philippines.

Lastly, of course, was Typhoon Haiyan, which formed in the Northwest Pacific Ocean on November 3. It first reached Category 5 strength on Wednesday, November 6 and maintained this strength for two days. At its peak, the sustained winds were up to 195 mph—higher than any other Category 5-level storms since 2000. It kept the high winds for a remarkable 48 hours.

Warm water is one of the major sources of fuel for tropical cyclones. In the Philippines, the mega-sized typhoon was able to retain its strength for so long because it continued to draw upon the surrounding warm water even as it had already started to cross over some of the central and southern islands.

At a UN Climate meeting in Poland last Monday, a Philippines climate delegate said about the recent storm: “It was so strong that if there was a Category 6, it would have fallen squarely in that box.” There is currently no chatter of creating a Category 6 level. As a National Hurricane Center spokesperson told me, the point is “moot” because Category 5 already covers widespread building destruction.

Regardless of whether a storm reaches wind speeds of 195 mph or 157 mph, however, it is going to cause massive destruction. Following the recent major storm, approximately 4 million people have been displaced. Nearly 13 million were impacted by the disaster, which damaged over 1 million houses, 628 schools, 77 day care centers, 48 health facilities and more. (To see the gruesome pictures of the Philippines following Haiyan, go here.)

According to the American hurricane intensity scale, called the Saffir-Simpson Hurricane Wind-Scale, “catastrophe damage will occur” at Cat 5 intensity. In other words, houses with some level of reinforcement will be destroyed and there will be total roof failure and wall collapse. Felled trees and power poles abound. Power outages could persist for weeks to months. “Most of the area will be uninhabitable for weeks or months.”

Zahra Hirji is natural hazards and emergency management junky. You can follow her on Twitter @zhirji28.

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