ABIO10 PGTW 281800 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN /OCEAN/281800Z-291800ZDEC2020// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/280751ZDEC2020// 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 28DEC20 0600Z, TROPICAL CYCLONE 07S (CHALANE) WAS LOCATED NEAR 20.0S 43.7E, APPROXIMATELY 236 NM EAST-NORTHEAST OF EUROPA ISLAND, AND HAD TRACKED WEST- SOUTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 35 KNOTS GUSTING TO 45 KNOTS. SEE REF A (WTXS31 PGTW 280900) FOR FURTHER DETAILS. (2) NO OTHER TROPICAL CYCLONES. B. TROPICAL DISTURBANCE SUMMARY: (1) THE AREA OF CONVECTION (INVEST 93S) PREVIOUSLY LOCATED NEAR 10.7S 91.8E IS NOW LOCATED NEAR 10.4S 90.0E, APPROXIMATELY 380 NM WEST-NORTHWEST OF COCOS ISLANDS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 281350Z GMI 89GHZ SATELLITE IMAGE DEPICT A BROAD LOW LEVEL CIRCULATION WITH FLARING CONVECTION OFFSET TO THE SOUTHWEST. A 281459Z ASCAT-A IMAGE SHOWS AN ELONGATED CIRCULATION WITH MOSTLY 10 KNOT WINDS IN THE NORTHERN SEMICIRCLE AND 15-20 KNOT WINDS IN THE SOUTHERN SEMICIRCLE WITH SOME PATCHES OF 25KTS. INVEST 93S IS CURRENTLY IN A MARGINALLY FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH WARM (28-29C) SEA SURFACE TEMPERATURES, GOOD OUTFLOW ALOFT, AND MODERATE TO STRONG (20-25 KNOTS) VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT INVEST 93S WILL TRACK GENERALLY SOUTHWESTWARD WITH LITTLE INTENSIFICATION OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW. (2) NO OTHER SUSPECT AREAS. C. SUBTROPICAL SYSTEM SUMMARY: NONE.// NNNN