Tropical Cyclone Herman Forms Northwest of Australia

Tropical Cyclone Herman formed over the South Indian Ocean northwest of Australia on Wednesday morning. At 5:00 a.m. EDT on Wednesday the center of Tropical Cyclone Herman was located at latitude 13.9°S and longitude 101.5°E which put it about 300 miles (480 km) east-southeast of Cocos Islands. Herman was moving toward the southwest at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 997 mb.

An area of low pressure over the South Indian Ocean east-southeast of Cocos Islands strengthened on Wednesday morning and the the Australian Bureau of Meteorology designated the system as Tropical Cyclone Herman. The inner end of a rainband wrapped around the western side of the center of Herman’s circulation. The strongest winds were occurring in the part of the band west of the center. Other bands of showers and thunderstorms were revolving around the center of Tropical Cyclone Herman. Storms near the center of circulation generated upper level divergence that pumped mass away from the tropical cyclone. Winds to tropical storm force extended out 160 miles (260 km) from the center of Herman’s circulation.

Tropical Cyclone Herman will move through an environment favorable for intensification during the next 24 hours. Herman will move over water where the Sea Surface Temperatures are near 28˚C. It will move under the western end of an upper level ridge over the eastern part of the South Indian Ocean. The ridge will produce northerly winds that will blow toward the top of Herman’s circulation. Those winds will cause some vertical wind shear, but the wind shear will not be enough to prevent intensification. Tropical Cyclone Herman is likely to strengthen during the next 24 hours. An upper level trough will approach Herman from the west on Thursday. The trough will cause the upper level winds to get stronger and the vertical wind shear will increase. More vertical wind shear will cause Tropical Cyclone Herman to weaken.

Tropical Cyclone Herman will move around the southwestern part of a high pressure system over the eastern South Indian Ocean. The high pressure system will steer Herman toward the southeast during the next 24 hours. On its anticipated track Tropical Cyclone Herman will move away from Cocos Islands. When Herman weakens later this week, it will be steered by the winds closer to the surface. Those winds will steer Tropical Cyclone Herman toward the west during the end of the week and the weekend.