UP prof: Typhoon like Yolanda unusual but not unheard of

MANILA, Philippines - A University of the Philippines (UP) professor said yesterday that weather systems as powerful as Super Typhoon Yolanda are unusual but not unheard of.

“(Yolanda) is unusual in a sense that a typhoon this strong does not form very often…but it is possible,” Gerry Bagtasa of the UP Institute of Environmental Science and Meteorology told The STAR.

“Once in a while, the condition is right for a strong typhoon to develop,” he added.

Bagtasa explained that most weather systems would not intensify into something as powerful as Yolanda because the condition and factors will not fall into place.

“But this time, the condition was right for it to intensify into something powerful,” said the professor, who also developed the website Weather-Manila.com that provides 4-day weather forecasts for different cities in the Philippines.

Bagtasa said Yolanda may be considered as the most powerful typhoon on record. The previous record holder was 1979 Typhoon Tip, which packed maximum sustained winds of 305 kilometers per hour (kph).

The Hawaii-based Joint Typhoon Warning Center (JTWC) said Yolanda, which it classified as a Category 5 storm, had maximum sustained winds of 315 kph and gusts reaching 380 kph last Friday.

Meanwhile, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) forecast the typhoon to have maximum sustained winds of around 225 kph and gustiness of 260 kph.

Bagtasa explained that the weather agencies had different predictions because PAGASA uses 10-minute average to record wind speed, while JTWC uses 1-minute average.

The data on Typhoon Tip was based on the 1-minute average measurement, thus confirming that Yolanda was stronger in terms of wind speed.

Climate change?

According to Bagtasa, the claims that the existence of powerful storms such as Yolanda was because of climate change may be attributed to studies showing an increase in the sea’s surface temperature.

He said that storms develop because of warm water, and that some people immediately linked the increase in the water temperature with the supposed increase in the number of weather systems that develop in recent years.

But he said he has not seen changes in the intensity and the number of typhoons that developed since the 1970s when data on the increase of seawater temperature became available.

“We don’t know yet the quantitative link (between the increase in water temperature and the formation typhoons). If the water temperature increased by one degree, what will be the changes in the wind speed and frequency of storms? We don’t know that,” he explained. 

Bagtasa also noted that more typhoons developed in the northwest Pacific Ocean in the 1960s than in recent years.– With Zinnia dela Peña, Rhodina Villanueva