Typhoon “Rolly” (international name “Goni”) has a slim chance to develop into a super typhoon, but the state weather bureau reminded the public to be prepared as it will still bring strong winds and intense rains over the country.
However, weather specialist Raymond Ordinario of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), said that the possibility is still not being ruled out as the typhoon continues to gain strength while moving over the Philippine waters.
“Maliit ang chance ngunit dahil nasa dagat pa, hindi natin nirurule out ang posibilidad na maging super typhoon si ‘Rolly’ but on the Philippine category, not JTWC category,” Ordinario said during a virtual press briefing.
(The chance is small but because it is still at sea, we do not rule out the possibility that ‘Rolly’ will develop into a super typhoon but in the Philippine category not the JTWC category.)
The Joint Typhoon Warning Center (JTWC) has forecasted that ‘Rolly’ will intensify into a super typhoon before its expected landfall over the Aurora-Quezon area between Sunday night and Monday morning.
PAGASA earlier explained that maximum sustained winds (MSW) from the JTWC of the United States are generally higher compared to the agency and other major meteorological centers as it uses 1 minute as wind averaging period for the estimation of MSW near the center.
This is different from PAGASA and other meteorological centers in the Western North Pacific which are using the World Meteorological Organization (WMO) recommended 10-minute averaging period.
The state weather agency added that meteorological centers use different thresholds for classifying tropical cyclones as a super typhoon.
For PAGASA, it classifies a tropical cyclone as a super typhoon when 10-minute MSW exceeds 220 kilometers, while JTWC’s super typhoon, when converted from 1 to 10-minute averaging, has MSW exceeding 185 kilometers per hour.
This means that on a 10-minute averaging, JTWC has a lower threshold for classifying super typhoons than PAGASA.
However, PAGASA pointed out that whether or not ‘Rolly’ will develop into a super typhoon, it is still strong and could bring devastating winds and rains especially in areas along its track.
Ordinario added that the typhoon is expected to reach a peak intensity of 195 kilometers per hour during its passage in the country, while the highest possible tropical cyclone wind signal that may be raised would be Signal No. 4 which means “destructive to very destructive typhoon-force winds” in areas directly in its path.
As of Friday afternoon, PAGASA said the typhoon is already at 980 kilometers east of Casiguran, Aurora and continues to move west at 20 kilometers per hour.
It further intensified and now has a maximum sustained winds of 185 kilometers per hour near the center and gusts of up to 230 kilometers per hour.
‘Rolly’ is the country’s 18th tropical cyclone for this year and the fifth for October alone.
Based on historical data, the Philippines gets an average of 20 tropical cyclones annually, but more rains are expected in the coming months according to PAGASA due to the onset of La Niña.