Tropical Cyclone Diane formed north of La Reunion on Friday. At 10:00 a.m. EST on Friday the center of Tropical Cyclone Diane was located at latitude 19.3°S and longitude 56.2°E which put it about 110 miles (175 km) north-northeast of St. Denis, La Reunion. Diane was moving toward the east-southeast at 18 m.p.h. (30 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 997 mb.
A distinct low level center of circulation developed in an area of low pressure east of Madagascar on Friday and the system was designated as Tropical Cyclone Diane. The distribution of thunderstorms around Tropical Cyclone Diane was asymmetrical. Many of the stronger thunderstorms were occurring northwest of the center of circulation. Bands of showers and thunderstorms were developing east of the center of Diane. Storms near the center of circulation were beginning to generate upper level divergence which was pumping mass away to the southeast of the tropical cyclone.
Tropical Cyclone Diane will move through an environment somewhat favorable for intensification during the next 24 to 36 hours. Diane will move over water where the Sea Surface Temperature is near 28°C. An upper level trough west of Madagascar and an upper level ridge east of Mauritius will interact to produce northwesterly winds which will blow toward the top of the tropical cyclone. Those winds will cause moderate vertical wind shear which will inhibit intensification. Tropical Cyclone Diane could intensify slowly during the next 24 to 36 hours.
The upper level trough and upper level ridge will steer Tropical Cyclone Diane toward the east-southeast during the next several days. On its anticipated track Tropical Cyclone Diane could bring wind and rain to Mauritius within 12 hours. Locally heavy rain could cause flash floods in some locations.