Utor's development following its naming was slow, but quickened as the tropical storm neared the Philippines. The tropical cyclone reached the southeastern coast of Samar by 06:00 UTC on December 9 and began tracking through the central Philippine archipelago over the next two days. Despite its interaction with the nearby islands, Utor continued to strengthen without much impediment and reached typhoon strength in the Visayan Sea at 12:00 UTC that day. Twelve hours later, the typhoon attained an initial peak intensity with maximum sustained winds of 140 km/h (85 mph) and a minimum barometric pressure of 955 mbar (hPa; 28.20 inHg) in the Sibuyan Sea according to the JMA. The JTWC analyzed an intensity of (185 km/h) 115 mph at that time. By 12:00 UTC on December 10, Utor had emerged into the South China Sea.