Typhoon Nina accelerated slightly as it traversed the open waters of the Philippine Sea. The storm continued to slowly deepen, though early on November 23, the system leveled off in intensity. That day, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) also monitored the storm and assigned it with the local name "Sisang", upon entering the Philippine Area of Responsibility. However, midday on November 24, Nina entered a phase of explosive intensification , at a rate of an hour. Despite this, the JMA only increased the intensity slightly to . After developing a well-defined eye, the JTWC reported that Nina attained its peak intensity of , making it a low-end Category 5 system on the Saffir-Simpson Hurricane Wind Scale. At 1500 UTC on November 25, Nina moved ashore along the southern tip of Luzon at its peak intensity.