Typhoon Kate (1970) - Meteorological History

Meteorological History

Super Typhoon Kate was first identified by the Joint Typhoon Warning Center (JTWC) on October 7, 1970, and by the Japan Meteorological Agency on October 9, 1970 as a tropical disturbance near the Marshall Islands. The system tracked in a general westward direction and relocated itself further south during this period in response to Typhoon Joan wake to the northwest. By October 13, convection sharply increased as the system entered a region of strong diffluence. The following day, the disturbance featured a marked increase in organization as thunderstorms continued to consolidate around the center of circulation. During the afternoon of October 15, reconnaissance aircraft reached the storm and reported that it was already nearing typhoon status. Sustained winds were measured at 110 km/h (70 mph) along with a barometric pressure of 985 mbar (hPa; 29.12 inHg). At this time cyclone storm was classified as Tropical Storm Kate, the 18th named storm of the 1970 season. Additionally, the storm had begun developing an eyewall, an indication that the system was likely to intensify further. Over the following three days, the storm continued its westward track while gaining strength.

Throughout the day on October 16, Kate underwent a period of rapid intensification. During this time, sustained winds increased from 140 km/h (85 km/h) to 215 km/h (135 mph), ranking Kate as a Category 4 hurricane on the modern day Saffir–Simpson Hurricane Scale. Early on October 17, reconnaissance planes flown into the typhoon measured the eye to be 18.5 km (11.5 mi) in diameter. Although winds were still increasing, the lowest pressure recorded in relation to Kate was measured at this time at 940 mbar (hPa; 27.7 inHg). As the typhoon neared the southeastern Philippine island of Mindanao on October 18, it further intensified. Just before making landfall roughly 45 km (30 mi) south of Davao City in the Davao Region, Kate attained its peak winds of 240 km/h (150 mph), classifying it as a super typhoon according to the JTWC, at the same time, JMA assessed that Kate had reached 10-minute sustained winds of 185 kph (130 mph)and a minimum central pressure of 940 mbar (28 inHg). As the storm moved over land, the eye abruptly shrank to 7.4 km (4.6 mi) in diameter but this feature dissipated hours later.

Due to the interaction with the mountainous terrain of the Philippines, Kate quickly weakened as it moved northwestward across the archipelago. By October 19, the system had weakened to a tropical storm, less than 24 hours after attaining its peak winds. Despite the notable weakening, the structure of the storm remained relatively intact as it moved over the Sulu Sea. Throughout the day, the system briefly sped up before rapidly slowing near the South China Sea. On October 20, decreased interaction with land allowed Kate to re-attain typhoon status just before passing over Busuanga Island. Continuing its northwest track, the typhoon slowly intensified and redeveloped a 37 mi (23 mi) wide eye. Late on October 21, the JTWC assessed the storm to have re-attained Category 4 intensity; however, post-storm analysis indicated that sustained winds did not exceed 195 km/h (125 mph). The following day, a ridge to the north of Kate prevented the system from tracking further north and prompted a west-southwestward track.

Gradual weakening took place over the following several days as Kate slowly neared the Indochina coastline. By October 24, winds had decreased below 155 km/h (100 mph) and the eye became asymmetrical and partially open in the northeast quadrant. On October 25, the typhoon further weakened to a tropical storm just off the coast of Vietnam. Later that day, the system made its final landfall near Da Nang, Vietnam with winds of 100 km/h (65 mph). Rapid weakening ensued as Kate moved over the high terrain of southwest Asia, with the storm degrading to a tropical depression within six hours of moving inland. The system dissipated within the next 24 hours as it moved over the plateau region of Cambodia. Both JTWC and JMA released their final advisories as Kate dissipated over Vietnam.