Tropical Cyclone Savannah Forms North of Cocos Island

Tropical Cyclone Savannah formed over the southeast Indian Ocean north of Cocos Island on Wednesday.  At 5:00 p.m. EDT on Wednesday the center of Tropical Cyclone Savannah was located at latitude 11.3°S and longitude 96.7°E which put it about 60 miles (100 km) north of Cocos Island.  Savannah was moving toward the south-southwest at 8 m.p.h. (13 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.  The Australian Bureau of Meteorology has issued a Tropical Storm Warning for Cocos Island.

More thunderstorms formed near an area of low pressure over the southeastern Indian Ocean west of Australia and the Australian Bureau of Meteorology designated the system as Tropical Cyclone Savannah.  The distribution of thunderstorms around Savannah was asymmetrical.  Several bands of showers and thunderstorms developed in the western half of the circulation.  Rainbands in the eastern half of the circulation consisted primarily of showers and lower clouds.  Tropical Cyclone Savannah was moving south of an upper level ridge.  The ridge was generating easterly winds which were blowing toward the top of the circulation.  Those winds were causing moderate vertical wind shear and they were contributing to the asymmetrical distribution of thunderstorms.

Tropical Cyclone Savannah will move through an environment favorable for intensification during the next several days.  Savannah will move over water where the Sea Surface Temperature is near 28°C.  The upper level ridge will continue to cause vertical wind shear, but the shear could decrease during the next 48 hours.  Tropical Cyclone Savannah is likely to intensify during the next day or two.

Tropical Cyclone Savannah will move near the western end of a strengthening subtropical ridge over Australia.  The ridge will steer Savannah toward the south-southwest during the next day or two.  On its anticipated track Tropical Cyclone Savannah will bring gusty winds and locally heavy rain to Cocos Island during the next 24 hours.