Typhoon Kammuri, known in the Philippines as Typhoon Tisoy, was a powerful typhoon which impacted the Philippines in early December 2019. Kammuri, which means Corona Borealis in Japanese, the twenty-eighth named storm and sixteenth typhoon of the 2019 Pacific typhoon season, Kammuri developed from a tropical wave situated a couple hundred kilometers south of the Mariana Islands. From November 25 to 27, the system tracked westward at a steady pace and rate of intensification, first making minor impacts in Guam. On November 28, the system intensified into a typhoon as environmental conditions became marginally conducive for significant development. From November 29 to December 1, Kammuri was unable to strengthen to previous estimates due to its near stationary movement as a result of weak steering currents, upwelling itself consequently. On December 2, the system tracked westward at a much faster speed of and rapidly intensified over warm Philippine Sea waters, before making landfall in the Bicol Region of the Philippines at peak intensity as a category 4-equivalent typhoon.
Upon leaving the Philippines, Kammuri significantly weakened as wind shear increased and interaction with the Philippine islands caused the structure of the system to degrade rapidly, and throughout December 3, it stayed as a category 1-equivalent typhoon, with its outer rainbands barely on land. By December 4, Kammuri drifted over the South China Sea as a weakening tropical storm. Through December 5 and 6, Kammuri weakened significantly and its low-level circulation center became exposed; as a result, it dissipated on December 6.
Meteorological history
On November 23, 2019, a low pressure system developed to the southeast of Guam. It then began to show signs of development and earned a defined circulation, developing into a tropical depression on November 25, with the JTWC assigning it as 29W. The depression then began to develop banding features to the northeast of its center, confirming intensification and allowing it to earn the name Kammuri (which is a Japanese name for Corona Borealis). Kammuri then passed south of Guam, and further intensified into a severe tropical storm on November 27, and then into a typhoon the next day. As the weak typhoon continued west, upwelling of itself due to its quasi-stationary movement combined with moderate wind shear hindered significant intensification of Kammuri over the next three days. It eventually entered the Philippine Area of Responsibility (PAR) with PAGASA assigning the name Tisoy on November 30. After entering the PAGASA's area of responsibility, Kammuri began to show signs of intensification again, and PAGASA noted the possibility of Kammuri making landfall in the Philippines as a somewhat powerful typhoon. After very slowly moving west and on approach to the Philippines, the system began to accelerate towards the Philippines and then began to rapidly intensify by the time it came within 321 kilometers of the coast of Catanduanes, due to the lowering of wind shear and increasing ocean heat content; all of which combined to counteract the upwelling. It became a category 2 typhoon and soon after, a category 3 typhoon. Kammuri reached its peak intensity as a 255 km/h category 4-equivalent typhoon on 07:00 UTC on December 2, and PAGASA reported that Kammuri had made its first landfall over Gubat, Sorsogon at 11:00 pm, December 2, very shortly after reaching its peak intensity.