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.

Tropical Cyclone Jenna moved farther away from the Cocos Islands on Tuesday.  At 4:00 p.m. EST on Tuesday the center of Tropical Cyclone Jenna was located at latitude 16.9°S and longitude 93.9°E which put the center about 380 miles (615 km) southwest of the Cocos, Islands.  Jenna was moving toward the southwest at 8 m.p.h. (13 km/h).  The maximum sustained wind speed was 90 m.p.h. (145 km/h) and there were wind gusts to 115 m.p.h. (185 km/h).  The minimum surface pressure was 976 mb.

Tropical Cyclone Jenna strengthened as it moved away from the Cocos Islands on Tuesday.  A small eye was visible at the center of Jenna’s circulation earlier on Tuesday.  The eye was no longer visible in the most recent satellite images.  A ring of thunderstorms surrounded the eye earlier today and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms revolved around the core of Tropical Cyclone Jenna.  Storms near the core of Jenna generated upper level divergence that pumped mass away from the tropical cyclone.

The size of the circulation around Tropical Cyclone Jenna increased on Tuesday.  Winds to hurricane/typhoon force extended out 25 miles (40 km) from the center of Jenna’s circulation.  Winds to tropical storm force extended out 160 miles (260 km) in the eastern side of Tropical Cyclone Jenna.  Winds to tropical storm force extended out 100 miles (160 km) in the western side of Jenna’s circulation.

Tropical Cyclone Jenna will move through an environment unfavorable for intensification during the next 24 hours.  Jenna will move over water where the Sea Surface Temperatures are near 27°C.  It will move under the southwestern part of an upper level ridge that is over the South Indian Ocean.  The upper level ridge will produce northwesterly winds that will blow toward the top of Jenna’s circulation.  Those winds will cause the vertical wind shear to increase. Tropical Cyclone Jenna will weaken when the vertical wind shear increases.

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

Tropical Cyclone Jenna rapidly intensified to the equivalent of a hurricane/typhoon over the South Indian Ocean on Monday.  At 4:00 p.m. EST on Monday the center of Tropical Cyclone Jenna was located at latitude 14.8°S and longitude 95.8°E which put the center about 160 miles (260 km) south-southwest of the Cocos, Islands.  Jenna was moving toward the south-southwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 987 mb.

The Australian Bureau of Meteorology cancelled the Warning for the Cocos Islands when Tropical Cyclone Jenna moved away from the islands.

Tropical Cyclone Jenna rapidly intensified to the equivalent of a hurricane/typhoon on Monday.  The inner end of a rainband wrapped around the center of Jenna’s circulation.  Bands of showers and thunderstorms were revolving around the center of Tropical Cyclone Jenna.  Storms near the center of Jenna generated upper level divergence that pumped mass away from the tropical cyclone.  The removal of mass caused the surface pressure to decrease rapidly.

The circulation around Tropical Cyclone Jenna was small.  The strongest winds were occurring in the northwestern quadrant of Jenna’s circulation.  Winds to hurricane/typhoon force extended out 25 miles (40 km) in the northwestern quadrant of Tropical Cyclone Jenna.  Winds to tropical storm force extended out 65 miles (105 km) from the center of Jenna’s circulation.

Tropical Cyclone Jenna will move through an environment favorable for intensification during the next 24 hours.  Jenna will move over water where the Sea Surface Temperatures are near 28°C.  It will move through a region where the upper level winds are weak and the will be little vertical wind shear.  Tropical Cyclone Jenna will intensify during the next 24 hours.

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