Typhoon Haiyan of the Philippines

Typhoon Haiyan was a huge weather system.  If you haven’t heard about the devastation caused by Typhoon Haiyan in the Philippines by now, then you probably don’t care… 

To date, Typhoon Haiyan is the strongest storm of the 2013 season and among the strongest ever on record to hit the Northwest Pacific Ocean region.  The Typhoon Haiyan was bound to leave a lot of damage in its wake.

In the hours before making landfall over the Philippines, the tropical cyclone (a generic term for hurricanes and typhoons) packed sustained winds of up to 305 kilometres per hour (about 190 miles per hour), according to some accounts.  Historically, it will likely go down as one of the five strongest storms in the last 50 years.

Super Typhoon Haiyan has been particularly significant among weather scientists, because it has been part of such a strange tropical cyclone season in the Northwest Pacific region.  The 2013 cyclone season started quite slowly and gradually accelerated, eventually setting a few records.

 

Recent Evolution and Dynamics of Storms in the Northwest Pacific Ocean

Hurricanes, cyclones, typhoons, storms, etc. are categorised in terms of pressure, sustained wind speeds and expected risk of damage.

This is the

From January to September 2013, 23 tropical cyclones formed in the Northwest Pacific Ocean.  Those tropical cyclones involve low pressure weather systems forming over warm tropical waters, with sustained gale force winds of 63 km/h or more.  Yet during that same time in the Northwest Pacific, only 5 typhoons with sustained wind gusts of more than 118 km/h formed in the region, when in an average season there would usually be 12 typhoons by the end of September.

Last month, the tropical cyclone activity accelerated, particularly when it came to the strength or intensity of the storms.

 

Making Landfall over Tacloban

Typhoon Haiyan was the 8th typhoon to hit the Northwest Pacific Ocean since the start of October 2013.  It formed near a latitude of 6°N on 3rd November, possibly in association with an equatorial Rossby wave, a westward moving atmospheric wave near the equator that can trigger convergence in the lower levels of the Earth’s atmosphere.

On 4th November 2013, Typhoon Haiyan attained the magnitude of a tropical cyclone, defined as having wind speeds greater than 63 km/h, and it continued to strengthen.

As a typhoon, the wind fields around Thyphoon Haiyan reached a maximum sustained wind strength of 232 km/h on 7th November 2013.

Just imagine what this could mean in terms of raw energy…

The sheer scale of the storm’s devastation made it comparable to the mayhem caused by the Indian Ocean Tsunami, which resulted from a magnitude 9.1 earthquake that struck the west of the island of Sumatra (Indonesia) on 26th December 2004.

Because the weather system of Typhoon Haiyan made landfall in a highly populated and vulnerable part of the Philippines coinciding with its peak intensity, its impact was devastating for the many communities it hit.

The coincident peak wind speeds occurring at landfall helped produce a significant storm surge – a phenomenon that leads to higher than normal tides and waves along coastal areas, and the single biggest threat to life in coastal areas from such weather events.  In 1970, the slightly less intense Bhola cyclone hit Bangladesh and up to 500,000 people died.  This fateful toll was mainly due to the associated storm surge.  However, in the case of Cyclone Monica in 2006, with a similar recorded intensity and storm surge to Haiyan, there were fortunately no fatalities because landfall occurred in a region that was sparsely populated.

Haiyan was estimated to have produced a storm surge of around 5 to 6 metres above normal tide level, inflicting significant damage and loss of life along the coastal fringe of the affected regions.  Undoubtedly, it is a potent reminder that continued improvements in forecasting accuracy, warning response, and community resilience will help save lives on the ground.

 

The Aftermath of Typhoon Haiyan

Again, if you haven’t seen the images of complete devastation and grief, you don’t care!

 

Typhoon Haiyan versus Hurricane Katrina

Americans are only too aware of the devastation caused by a cyclone.  Hurricane Katrina (on the left) was the deadliest and most destructive Atlantic tropical cyclone of 2005.

If we compare images of both weather events, Hurricane Katrina (left) was an intense hurricane, yet compared to Super Typhoon Haiyan (on the right), we can get an idea of how strong Haiyan was at its peak intensity.

Deeper red colours indicate colder cloud tops, indicative of more intense convection.  The right image shows just how intense Super Typhoon Haiyan was at the height of its power. 

While the satellite image of Typhoon Haiyan shows colder cloud tops – an evidence of greater intensity – comparing it to Katrina seems a bit like comparing apples and oranges.  Almost literally by the look of those pictures!

Although the storms may be comparable in size in terms of cloud cover, a more scientific comparison involve their actual wind fields.  Astonishingly, Hurricane Katrina’s wind fields of tropical storm-force and hurricane-force winds were each nearly twice as large as that of Typhoon Haiyan’s, indicating that the radius of destruction was also larger for Katrina.

However, Typhoon Haiyan will go down in history as one of the most intense tropical systems ever witnessed on our beloved planet Earth.  It seems clear that the Saffir–Simpson Scale does not cater for such a large-scale weather event.  There is as yet no category corresponding to such wind speeds exceeding the 252 km/h mark.  With time, a continuous mathematical restatement of the Saffir-Simpson Hurricane Scale should be made with the addition of a new category.  A Category 6 Hurricane?

Most observations of the storm were taken from space, and satellites played an important role in determining Typhoon Haiyan’s critical statistics.  Satellites also gave the world a stunning look at the storm as it progressed toward a collision course with the Philippines.

It also beat the wind speed record of Hurricane Camille in 1969, another Category 5 hurricane, the second of three catastrophic hurricanes to make landfall in the United States during the 20th century.

The next video shows the extent of Super Typhoon Haiyan as observed from the International Space Station.

It all looks so deceptively peaceful from up there…