ABIO10 PGTW 311800 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN OCEAN/311800ZDEC2023-011800ZJAN2024// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/311351ZDEC2023// AMPN/REF A IS A TROPICAL CYCLONE WARNING.// RMKS/ 1. NORTH INDIAN OCEAN AREA (MALAY PENINSULA WEST TO COAST OF AFRICA): A. TROPICAL CYCLONE SUMMARY: NONE. B. TROPICAL DISTURBANCE SUMMARY: NONE. C. SUBTROPICAL SYSTEM SUMMARY: NONE. 2. SOUTH INDIAN OCEAN AREA (135E WEST TO COAST OF AFRICA): A. TROPICAL CYCLONE SUMMARY: (1) AT 31DEC23 1200Z, TROPICAL CYCLONE 04S (ALVARO) WAS LOCATED NEAR 20.4S 39.0E, APPROXIMATELY 127 NM NORTH-NORTHWEST OF EUROPA ISLAND, AND HAD TRACKED EAST- SOUTHEASTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 35 KNOTS GUSTING TO 45 KNOTS. SEE REF A (WTXS31 PGTW 311500) FOR FURTHER DETAILS. (2) NO OTHER TROPICAL CYCLONES. B. TROPICAL DISTURBANCE SUMMARY: NONE. C. SUBTROPICAL SYSTEM SUMMARY: NONE.// NNNN