Bising (Surigae), which was a typhoon at its peak, left the Philippine Area of Responsibility (PAR) as a tropical storm at 5:40 am on Sunday, April 25.

Its exit came 9 days after it entered PAR on April 16.

Then at 8 am on Sunday, Bising transitioned into a gale-force extratropical cyclone, said the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) in a bulletin issued 11 am.

An extratropical cyclone is a “low pressure system which develops in latitudes outside the tropics,” according to the World Meteorological Organization.

In addition, an extratropical cyclone gets energy “from the temperature contrast between warm and cold air masses,” according to the United States’ National Hurricane Center. A tropical cyclone, meanwhile, is fueled by warm air.

The extratropical cyclone which used to be Bising was last spotted 1,500 kilometers east of extreme Northern Luzon on Sunday morning.

Though it is already outside PAR, it is still expected to have an impact on coastal waters in the next 24 hours.

PAGASA warned of moderate to rough waters in the following seaboards:

• northern and eastern seaboards of Northern Luzon (waves 1.5 to 3.5 meters high)
• eastern seaboards of Central Luzon and Southern Luzon (waves 1.2 to 3 meters high)

The state weather bureau advised small vessels and “inexperienced mariners” not to venture out to sea.

Image from PAGASA

Bising, the country’s second tropical cyclone for 2021, did not make landfall. But while over the Philippine Sea, it triggered heavy rain that caused floods and landslides.

As a typhoon, Bising had reached maximum sustained winds of 215 km/h. If it had exceeded 220 km/h, it would have been a super typhoon. (READ: FAST FACTS: Tropical cyclones, rainfall advisories)

Signal No. 2 was the highest tropical cyclone wind signal that was raised due to Bising. Higher wind signals were not raised as it stayed offshore.

The National Disaster Risk Reduction and Management Council said Bising left at least 4 people dead and 13 others injured in Bicol, Central Visayas, Eastern Visayas, and Davao Region.

For the next 6 months, PAGASA estimates the following number of tropical cyclones inside PAR:

• May – 0 or 1
• June – 1 or 2
• July – 1 to 3
• August – 2 or 3
• September – 2 or 3
• October – 2 or 3

The Philippines gets around 20 tropical cyclones each year. (READ: LIST: PAGASA’s names for tropical cyclones in 2021) – Rappler.com