Large Typhoon Mindulle developed concentric eyewalls southwest of Iwo To on Sunday. At 11:00 p.m. EDT on Sunday the center of Typhoon Mindulle was located at latitude 19.9°N and longitude 136.4°E which put it about 445 miles (720 km) southwest of Iwo To. Mindulle moving toward the north at 3 m.p.h. (5 km/h). The maximum sustained wind speed was 125 m.p.h. (200 km/h) and there were wind gusts to 150 m.p.h. (240 km/h). The minimum surface pressure was 947 mb.

Typhoon Mindulle developed concentric eyewalls on Sunday when the inner end of a rainband wrapped around an existing eye and eyewall. When the larger outer eyewall formed, much of the low level convergence of air shifted to the outer eyewall. The inner eyewall began to weaken because there was less low level convergence into it. Since the strongest winds were occurring in the existing inner eyewall, the maximum wind speed decreased when it weakened. The inner eyewall was still present, although it was much weaker. There was a break in the northwestern part of the outer eyewall. The existence of the two eyewalls was disrupting the inner core of Typhoon Mindulle.

The ongoing Eyewall Replacement Cycle was causing the circulation around Typhoon Mindulle to get larger. Winds to typhoon force extended out 65 miles (105 km) from the center of Mindulle. Winds to tropical storm force extended out 205 miles (330 km) from the center of circulation. The Hurricane Intensity Index (HII) for Typhoon Mindulle was 23.6. The Hurricane size Index (HSI) was 23.2 and the Hurricane Wind Intensity Size Index (HWISI) was 46.8.

Typhoon Mindulle will move through an environment capable of sustaining a powerful typhoon during the next 36 hours. Mindulle will move over water where the Sea Surface Temperatures are near 30˚C. It will move into a region where the upper level winds are weak and there will be little vertical wind shear. The ongoing Eyewall Replacement Cycle will likely cause Typhoon Mindulle to weaken during the next 12 hours. If the inner eyewall dissipates and the outer eyewall becomes more well developed, then Mindulle could strengthen again. Typhoon Mindulle will move slowly. The strong winds in Mindulle could mix cooler water to the surface. Cooler water and an Eyewall Replacement Cycle could limit the potential for Typhoon Mindulle to intensify.

Typhoon Mindulle will move around the western end of a subtropical high pressure system over the Western North Pacific Ocean during the next several days. The high will steer Mindulle slowly toward the north-northwest during the next 36 hours. On its anticipated track Typhoon Mindulle could be west of Iwo To in 48 hours. Mindulle could be south of Tokyo in four days.