Typhoon Mawar Weakens a Little

Typhoon Mawar weakened a little on Saturday as it moved over the Western North Pacific Ocean south of the Ryukyu Islands. At 11:00 a.m. EDT on Saturday the center of Typhoon Mawar was located at latitude 16.9°N and longitude 130.4°E which put it about 650 miles (1050 km) southeast of Ishigakijima, Japan. Mawar was moving toward the west-northwest at 15 m.p.h. (24 km/h). The maximum sustained wind speed was 150 m.p.h. (240 km/h) and there were wind gusts to 185 m.p.h. (295 km/h). The minimum surface pressure was 926 mb.

Typhoon Mawar weakened a little after it went through another eyewall replacement cycle. The previous inner eye and eyewall dissipated. However, a circular eye with a diameter of 30 miles (50 km) was present at the center of Mawar’s circulation. The eye was surrounded by a broken ring of thunderstorms and the strongest winds were occurring in that ring of storms. Numerous bands of showers and thunderstorms were revolving around the center of Typhoon Mawar. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical storm in all directions. The upper level divergence was not able to remove as much mass as was converging in the lower levels of Mawar’s circulation which caused the surface pressure to increase slowly.

The recent eyewall replacement cycle caused the size of the circulation around Typhoon Mawar to remain large. Winds to typhoon force extended out 80 miles (130 km) from the center of Mawar’s circulation. Winds to tropical storm force extended out 275 miles (445 km) from the center of Mawar. The Hurricane Intensity Index (HII) for Typhoon Mawar was 31.6. The Hurricane Size Index (HSI) was 30.0 and the Hurricane Wind Intensity Size Index (HWISI) was 61.6. Typhoon Mawar was similar in size and intensity to Hurricane Wilma when Wilma was over the Northwest Caribbean Sea in 2005.

Typhoon Mawar will move through an environment favorable for a powerful typhoon during the next 24 hours. Mawar will move over water where the Sea Surface Temperatures are near 30˚C. It will move under the the axis of an upper level ridge over the Western North Pacific Ocean. The upper level winds are weak near the axis of the ridge and there will be little vertical wind shear. Although the environment is favorable, the recent eyewall replacement cycle partially disrupted the inner core of Typhoon Mawar. Since the upper level divergence is removing less mass than is converging in the lower levels, the surface pressure is likely to increase slowly. If the surface pressure continues to increase, Typhoon Mawar will weaken gradually during the next 24 hours.

Typhoon Mawar will move around the southern part of a subtropical high pressure system over the Western North Pacific Ocean. The high pressure system will steer Mawar toward the west-northwest during the next 24 hours. On its anticipated track, Typhoon Mawar could move south of Ishigakijima, Japan in 48 hours.