With typhoons or hurricanes, rapid intensification is an increase in maximum sustained winds of 35 mph (55 kph) in 24 hours.
From Tuesday afternoon to Wednesday afternoon, Vongfong easily met that definition, strengthening from a modest tropical storm with winds of 60 mph (95 kph) to the equivalent of a major hurricane. Maximum sustained winds are now up to 120 mph (195 kph) and the storm is still strengthening.
This area of the world is no stranger to rapid intensification. Many storms undergo rapid intensification each year due to the extremely warm sea surface temperatures.
But this is the first named storm of the season in the West Pacific.
It didn’t exist until Tuesday, and now it will hammer the Philippines as the equivalent of a category 3 or 4 storm on the Saffir-Simpson scale.
Weather models had difficulty forecasting the intensity of Vongfong, in part because of the small size of the storm.
Now that the storm has intensified so quickly there is no doubt that it will be more than a rainmaker when it reaches the coast.
“Very heavy rainfall, damaging winds, and powerful storm surge are all major concerns with this storm,” CNN Meteorologist Tom Sater said.
“One silver lining with this being a small storm is that the strong typhoon strength winds only extend out about 25 kilometers from the center.”
While the damaging winds will only occur right along the immediate path of the storm, heavy rain will have a more widespread impact.
Rainfall amounts of 100 to 250 mm (four to 10 inches) will impact vast areas of the Visayas and Bicol Regions through northern Luzon.
Vongfong will pass just offshore of Samar province Thursday, before making its first landfall in the Bicol region, north of Legazpi Thursday night local time.
After hitting the Bicol region, the storm will retain most of its strength and move into northeastern Luzon Friday night.
“There is a possibility that the center of the storm could stay just offshore,” Sater said. “It’s not a great chance, but if the forecast shifts just 50 kilometers to the east, it would keep the worst of the winds and storm surge offshore.”
Slow start to the 2020 typhoon season
The West Pacific typhoon season doesn’t have a defined beginning and end like the Atlantic hurricane season, as storms can form throughout the year.
While the peak of the typhoon season is late summer, there are frequently named storms in the winter or early spring due to the warm waters of the Pacific.
This is the eighth-latest start to the season since 1950, according to Phil Klotzbach, a research scientist at Colorado State University. The last time we had a later start was 2016 when the first named storm of the season didn’t arrive until the first week of July.
The Philippines are located in the prime breeding grounds of the tropical Pacific. In an average year, the region is impacted by eight to nine storms.
Late-starting seasons tend to be slightly quieter, but the evidence is weak, according to Klotzbach.