ABIO10 PGTW 031800 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN /OCEAN/031800Z-041800ZAPR2021// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/031351ZAPR2021// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// 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: NONE. B. TROPICAL DISTURBANCE SUMMARY: (1) THE AREA OF CONVECTION (INVEST 99S) PREVIOUSLY LOCATED NEAR 11.0S 122.3E IS NOW LOCATED NEAR 10.7S 123.8E, APPROXIMATELY 209 NM NORTH OF BROWSE ISLAND, AUSTRALIA. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY AND A 031054Z SSMIS 91GHZ MICROWAVE PARTIAL IMAGE DEPICT FORMATIVE CONVECTIVE BANDING WARPPING INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). A 031148Z METOP-A ASCAT PASS REVEALS A TIGHT LLCC WITH A SWATH OF 30-35 KT WINDS IN THE SOUTHERN PERIPHERY. 90S IS CURRENTLY IN A FAVORABLE ENVIRONMENT WITH WARM (30 CELSIUS) SEA SURFACE TEMPERATURES (SST) AND DUAL CHANNEL OUTFLOW BEING SLIGHTLY OFFSET BY LIGHT TO MODERATE (10-20 KNOT) VERTICAL WIND SHEAR (VWS). GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 99S WILL REMAIN QUASISTAIONARY AS IT CONSOLIDATES AND INTENSIFIES. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 2 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH. SEE REF A (WTXS21 PGTW 031400) FOR FURTHER DETAILS. (2) THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR 9.5S 103.3E IS NOW LOCATED NEAR 10.8S 102.9E, APPROXIMATELY 168 NM WEST OF CHRISTMAS ISLAND. ANIMATED EIR SATELLITE IMAGERY AND A 031328Z METOP-A 89GHZ MICROWAVE IMAGE DEPICT FRAGMENTED DEEP CONVECTION EMBEDDED IN FORMATIVE BANDS WRAPPING AROUND AN ELONGATED AND OBSCURED LOW LEVEL CIRCULATION. 90S IS CURRENTLY IN A FAVORABLE ENVIRONMENT WITH WARM (30 CELSIUS) SST, LOW (05-10 KNOT) VWS, AND EXCELLENT POLEWARD OUTFLOW. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 90S WILL CONTINUE TO TRACK GENERALLY SOUTHEASTWARD, REMAINING ELONGATED WHILE INTENSIFYING, POTENTIALLY REACHING WARNING THRESHOLD IN 2 TO 3 DAYS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM. (3) NO OTHER SUSPECT AREAS. C. SUBTROPICAL SYSTEM SUMMARY: NONE.// NNNN