Bising leaves PAR, transitions into extratropical cyclone Apr 25, 2021 12:45 PM PHT 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.