ABIO10 PGTW 040830
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN OCEAN
/REISSUED/040830Z-041800ZAPR2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/031351ZAPR2021//
REF/B/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/040752ZAPR2021//
NARR/REFS A AND B ARE TROPICAL CYCLONE FORMATION ALERTS.//
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 10.7S 123.8E IS NOW LOCATED NEAR 10.4S 123.9E, APPROXIMATELY 
242 NM NORTH OF BROWSE ISLAND, AUSTRALIA. ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY AND A 040457Z AMSR2 GW1 89GHZ MICROWAVE IMAGE 
DEPICT FRAGMENTED DEEP CONVECTIVE BANDING SURROUNDING A PARTIALLY 
OBSCURED LOW LEVEL CIRCULATION CENTER (LLCC). 99S IS CURRENTLY IN A 
MARGINAL ENVIRONMENT WITH WARM (30 CELSIUS) SEA SURFACE TEMPERATURES 
AND EXCELLENT EQUATORWARD OURFLOW BEING OFFSET BY UNFAVORABLE (20 TO 
30 KNOTS) VERTICAL WIND SHEAR AND LAND INTERACTION AS THE LLCC STAYS 
NEAR THE ISLAND OF TIMOR-LESTE. GLOBAL MODELS ARE IN GOOD AGREEMENT 
THAT 99S WILL STRUGGLE TO FULLY CONSOLIDATE WHILE IT REMAINS NEAR 
LAND; HOWEVER, AFTER IT BEGINS TO TRACK SOUTHWESTWARD, 
INTENSIFICATION TO WARNING THRESHOLD WILL OCCUR IN 6 TO 18 HOURS. 
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. 
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 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 10.8S 102.9E IS NOW LOCATED NEAR 13.8S 105.2E, APPROXIMATELY 
203 NM SOUTH OF CHRISTMAS ISLAND. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY AND A 040634Z AMSR2 GW1 89GHZ MICROWAVE IMAGE DEPICT 
PERSISTENT DEEP CONVECTION OVERHEAD A SLIGHTLY ELONGATED LOW LEVEL 
CIRCULATION CENTER (LLCC) WITH DEVELOPING DEEP CONVECTIVE BANDING 
TIGHTLY WRAPPING IN FROM THE EAST. THE OVERALL CONVECTIVE STRUCTURE 
REMAINS VERY ASYMMETRIC WITH VERY LITTLE CONVECTIVE SIGNATURE IN THE 
WESTERN SEMICIRCLE. A 040246Z METOP-C ASCAT PASS REVEALS A HIGHLY 
ASYMMETRIC WIND FIELD WITH ENHANCED (25 TO 30 KNOT) WINDS TURNING 
AROUND THE SOUTHERN EDGE OF THE ELONGATED LLCC AND WEAKER (5 TO 10 
KNOT) WINDS CONSIGNED TO THE NORTH. 90S IS CURRENTLY IN A FAVORABLE 
ENVIRONMENT WITH WARM (30 CELSIUS) SEA SURFACE TEMPERATURES, LOW (5 
TO 10 KNOTS) VERTICAL WIND SHEAR, AND EXCELLENT POLEWARD OUTFLOW; 
HOWEVER, THE HIGH TRACK SPEEDS MAY BE SLIGHTLY OFFSETTING THE 
ENVIRONMENTAL FACTORS. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 90S 
WILL REMAIN ELONGATED AND ASYMMETRIC AS IT TRACKS SOUTHEAST AND 
INTENSIFIES, REACHING WARNING THRESHOLD WITHIN 36 HOURS. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR 
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 
HOURS IS UPGRADED TO HIGH. SEE REF B (WTXS22 PGTW 04800) FOR FURTHER 
DETAILS.
      (3) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN PARA 2.B.(2) TO 
HIGH.//
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