 On December 23 , a circulation with accompanying convection became evident about 400 km ( 250 mi ) southeast of Diego Garcia , becoming a tropical disturbance . While moving to the south , the thunderstorms organized more , aided by low wind shear , good outflow , warm waters , and its position beneath an anticyclone . Curving west @-@ southwestward due to a ridge to the south , the system intensified into a tropical depression and later Tropical Storm Astride on December 25 . That day , the JTWC classified the system as Tropical Cyclone 03S . The storm developed a large area of convection , prompting the MFR to upgrade it to a severe tropical storm on December 26 , estimating 10 ‑ minute winds of 95 km / h ( 60 mph ) . On December 27 , the JTWC upgraded Astride to the equivalent of a minimal hurricane due to the appearance of an eye feature , estimating 1 ‑ minute winds of 120 km / h ( 75 mph ) . Later that day , the storm weakened unexpectedly , perhaps related to wind shear from a trough to the south . The convection deteriorated markedly , and the weakening storm turned more to the west @-@ northwest on December 29 due to a weaker ridge . Convection reorganized slightly , although it was dislocated from the center . Early on December 30 , the storm passed about 70 km ( 45 mi ) northeast of Tromelin Island . Curving back to the west , Astride struck northeastern Madagascar between Vohemar and Antsiranana on December 31 as a minimal tropical storm . It emerged into the Mozambique Channel as a tropical depression , and despite forecasts to the contrary , it reintensified into a tropical storm before passing near Mayotte on January 2 . Early the next day , Astride weakened back to tropical depression status before moving ashore eastern Mozambique near Pemba , dissipating soon after . 
