After attaining typhoon status, Paka strengthened fairly quickly, and by December 12 it reached sustained winds of 150 km/h (90 mph) for a ten-minute (10 min) duration, or 215 km/h (135 mph) over a one-minute (1 min) duration. Subsequently, it briefly weakened as its forward motion increased. However, Paka again re-intensified, and at 1200 UTC on December 14 it attained the unofficial ranking of Category 5 super typhoon status while over the open Pacific Ocean with estimated 1-minute sustained winds of 260 km/h (160 mph). At the same time, the JMA classified it with 10 min sustained winds of 175 km/h (110 mph). After reaching its initial peak intensity, Paka underwent an eyewall replacement cycle and began weakening as it approached the southern Mariana Islands; the NEXRAD Doppler weather radar from Guam revealed the presence of a primary eyewall of 74 km (46 mi) in diameter, with a fragmented inner wall cloud of 19 km (11 mi) in diameter. Additionally, satellite imagery indicated an eyewall mesovortex within the eye of the typhoon. It slowed and began to re-intensify as it continued westward, and at 0530 UTC on December 16 the northern portion of the outer eyewall of Paka passed over the island of Rota; 20 minutes later, the southern portion of the inner wall cloud moved across northern Guam. As it tracked through the Rota Channel, the center of Paka passed about 8 km (5 mi) north of the northern tip of Guam, its closest approach to the island.