Tropical Cyclone Jenna weakened on Wednesday as it moved over the South Indian Ocean southwest of the Cocos Islands.  At 4:00 p.m. EST on Wednesday the center of Tropical Cyclone Jenna was located at latitude 18.6°S and longitude 90.9°E which put the center about 580 miles (940 km) southwest of the Cocos Islands.  Jenna was moving toward the west-southwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h).  The minimum surface pressure was 993 mb.

Tropical Cyclone Jenna weakened steadily on Wednesday as it moved southwest of the Cocos Islands.  The southwestern part of an upper level ridge produced strong northwesterly winds that blew toward the top of Jenna’s circulation.  Those winds caused strong vertical wind shear.  The strong upper level winds also blew the tops off of many of the thunderstorms that were part of Tropical Cyclone Jenna.

There were few thunderstorms left in Tropical Cyclone Jenna because of the strong vertical wind shear.  The bands revolving around the center of Jenna’s circulation consisted primarily of showers and lower clouds.  There was little upper level divergence.  Mass was still converging in the lower levels of the atmosphere.  So, the convergence of mass caused the surface pressure to increase.

The strong vertical wind shear also caused the distribution of wind speeds in Tropical Cyclone Jenna to become more asymmetrical.  Winds to tropical storm force extended out 100 miles (160 km) in the southern side of Jenna’s circulation.  Tropical storm force winds extended out 35 miles (55 km) in the northern side of Tropical Cyclone Jenna.

Tropical Cyclone Jenna will move through an environment very unfavorable for intensification during the next 24 hours.  Jenna will move over water where the Sea Surface Temperatures are near 26°C.  It will continue to move under the southwestern part of an upper level ridge that is over the South Indian Ocean.  The upper level ridge will continue to produce strong northwesterly winds that will blow toward the top of Jenna’s circulation.  Those winds will continue to cause strong vertical wind shear.  Tropical Cyclone Jenna will continue to weaken because of the strong vertical wind shear.

Tropical Cyclone Jenna will move around the northern side of a high pressure system that is over the South Indian Ocean.  The high pressure system will steer Jenna toward the west during the next 24 hours.  On its anticipated track, Tropical Cyclone Jenna will continue to move farther away from the Cocos Islands.