Tropical Cyclone Jobo moved toward Tanzania on Thursday. At 11:00 p.m. EDT on Thursday the center of Tropical Cyclone Jobo was located at latitude 9.1°S and longitude 43.6°E which put it about 335 miles (535 km) east-southeast of Dar es Salaam, Tanzania. Jobo was moving toward the west-northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h). The minimum surface pressure was 992 mb.
The intensity and organization of Tropical Cyclone Jobo fluctuated during the past 48 hours as the strength of the upper level winds changed. At times Jobo intensified to the equivalent of a strong tropical storm when the upper levels winds diminished. Whenever the upper level winds were stronger, vertical wind shear caused the circulation to weaken. Tropical Cyclone Jobo was intensifying again on Thursday night. The inner end of a rainband wrapped around the southern and western sides of the center of circulation. Thunderstorms near the center generated more upper level divergence that pumped mass away from the tropical cyclone. The circulation of Tropical Cyclone Jobo was small, which was why vertical wind shear had such a big effect on the tropical cyclone. Winds to tropical storm force extended out 80 miles (130 km) from the center of circulation.
Tropical Cyclone Jobo will move through an environment favorable for intensification during the next 36 hours. Jobo will move over water where the Sea Surface Temperatures will be near 29°C. Jobo will move under the middle of an upper level ridge over southern Africa and the Southwest Indian Ocean. The winds are weaker near the middle of the ridge and there will be less vertical wind shear. Tropical Cyclone Jobo could strengthen during the next 36 hours, but any increase in the wind shear could cause the small circulation to weaken again.
Tropical Cyclone Jobo will move around the northern side of a subtropical high pressure system over southern Africa. The high will steer Jobo toward the west-northwest during the next several days. On its anticipated track Tropical Cyclone Jobo could approach the coast of Tanzania in 36 hours.
Tropical Cyclone Berguitta intensified into the equivalent of a hurricane/typhoon on Sunday. At 10:00 p.m. EST on Sunday the center of Tropical Cyclone Berguitta was located at latitude 17.8°S and longitude 63.1°E which put it about 415 miles (670 km) east-northeast of Port Louis, Mauritius. Berguitta was nearly stationary. 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 985 mb.
The circulation of Tropical Cyclone Berguitta continued to get better organized on Sunday. An eye appeared intermittently at the center of circulation. The eye was surrounded by an elliptical ring of thunderstorms and the strongest winds were occurring in those storms. Bands of showers and thunderstorms were revolving around the core of the circulation. Storms near the center of Berguitta were generating upper level divergence which was pumping mass away from the center of circulation.
Tropical Cyclone Berguitta will continue to move through an environment favorable for intensification during the next several days. Berguitta will move over water where the Sea Surface Temperature is near 28°C. The upper level winds are weak and there is little vertical wind shear. Tropical Cyclone Berguitta will continue to strengthen and it could intensify into the equivalent of a major hurricane.
Tropical Cyclone Berguitta is moving in a region where the steering winds are weak. Berguitta moved little on Sunday. A subtropical ridge south of Berguitta is forecast to steer the tropical cyclone slowly westward during the next 24 to 48 hours. Berguitta will near the western end of the ridge in about two days and it is likely to move toward the southwest after that time. On its anticipated track Tropical Cyclone Berguitta could reach Mauritius within 72 hours.
The core of Tropical Cyclone Berguitta could move very close to Mauritius and La Reunion. Berguitta could be the equivalent of a major hurricane at that time. It has the potential to cause major wind damage, a storm surge, heavy rain and floods.
Elsewhere over the South Indian Ocean microwave images of Invest 99S depicted a structure that looked very much like a tropical cyclone. At 10:00 p.m. EST on Sunday the center of Invest 99S was centered at latitude 15.1°S and longitude 41.6°E which put it about 75 miles (120 km) east of Lumbo, Mozambique. Microwave satellite images showed a clear area at the center of circulation surrounded by broken ring of showers and thunderstorms. A primary rainband wrapped around the eastern side of the circulation and secondary bands of showers and thunderstorms existed in all quadrants of the circulation. However, no official government agency is classifying the system as a tropical cyclone at the current time.
Thunderstorms near the center of Tropical Cyclone Fantala dissipated and it weakened as moved northeast of Madagascar. At 5:00 p.m. EDT on Saturday the center of Tropical Cyclone Fantala was located at latitude 11.5°S and longitude 54.5°E which put it about 350 miles (565 km) east of Antsirañana, Madagascar. Fantala was moving west-northwest at 10 m.p.h. (16 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 988 mb.
Tropical Cyclone Fantala reversed course again on Saturday and it is moving over the same part of the South Indian Ocean that it already crossed twice during the past few days. The winds produced by Fantala mixed cooler water up to to the surface of the ocean during its previous passages over the same region. The cooler water means that there is less energy available to power the circulation of Tropical Cyclone. Although the winds continue to rotate around the center of circulation, there are no thunderstorms near the core of Fantala. There are still several thunderstorms in rainbands farther to the east of the center of circulation.
If new thunderstorms do not develop around the core of the circulation, the winds will gradually spin down and the tropical cyclone will dissipate within a few days. Upper level winds blowing from the west-northwest are also generating some vertical wind shear, which will make it more difficult for new thunderstorms to form.
A subtropical ridge southwest of Fantala is steering the tropical cyclone toward the west-northwest and that general motion is expected to continue for the next several days. On its anticipated track Tropical Cyclone Fantala is forecast to pass north of Madagascar and move over the Seychelles. It could be even weaker by the time it gets to the Seychelles.
Tropical Cyclone Fantala moved into an area of weaker steering currents on Thursday and it stalled about 500 miles (800 km) east of northern Madagascar. At 5:00 p.m. EDT on Thursday the center of Tropical Cyclone Fantala was located at latitude 13.0°S and longitude 56.7°E which put it about 515 miles (830 km) east of Antsirañana, Madagascar. Fantala was moving toward the southeast at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 95 m.p.h. (155 km/h) and there were wind gusts to 115 m.p.h. (185 km/h). The minimum surface pressure was 963 mb.
Although Fantala weakened slightly on Thursday, the structure of the inner core of the circulation remained fairly intact. A thin ring of thunderstorms was wrapped around an that was obscured on conventional satellite imagery. Other bands of thunderstorms spiraled around the eyewall. The thunderstorms in the core of Fantala were generating upper level divergence to the north and east of the center of circulation. It appears that drier air may be getting pulled into the eastern portion of the circulation outside the core of Fantala. There only only isolated thunderstorms in the rainbands in that part of the circulation.
The environment is marginally favorable for intensification. The upper level winds are light enough so there is only a moderate amount of vertical wind shear. Fantala is over water where the Sea Surface Temperature is near 29°C. However, because Fantala is moving so slowly, it could mix cooler water to the surface which would reduce the energy available to the tropical cyclone. In addition the drier air will also limit the supply of energy being transported into the core of the circulation.
Tropical Cyclone Fantala has moved into an area where the steering currents are weak. It may not move much during the next 24 hours. A subtropical ridge is forecast to develop southwest of Fantala in a day or two. When the subtropical ridge develops, it is expected to steer Fantala back toward the west again. On its anticipated track Tropical Cyclone Fantala could be approaching the northern part of Madagascar in 60 to 72 hours.