ABIO10 PGTW 101800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN 
OCEAN/101800Z-111800ZAPR2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/101351ZAPR2021//
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 10APR21 1200Z, TROPICAL CYCLONE 26S (SEROJA) WAS 
LOCATED NEAR 21.5S 108.7E, APPROXIMATELY 304 NM WEST OF LEARMONTH, 
AUSTRALIA, AND HAD TRACKED SOUTHEASTWARD AT 08 KNOTS OVER THE PAST 
SIX HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 60 
KNOTS GUSTING TO 75 KNOTS. SEE REF A (WTXS31 PGTW 101500) FOR 
FURTHER DETAILS.
      (2) NO OTHER TROPICAL CYCLONES.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION (INVEST 91S) PREVIOUSLY LOCATED 
NEAR 13.3S 100.0E IS NOW LOCATED NEAR 13.9S 101.6E, APPROXIMATELY 
314 NM SOUTHWEST OF CHRISTMAS ISLAND. ANIMATED ENHANCED INFRARED 
(EIR) SATELLITE IMAGERY AND A 100959Z SSMIS 91GHZ MICROWAVE IMAGE 
REVEAL DISORGANIZED CYCLING CONVECTION IN THE EASTERN PERIPHERY OF A 
BROAD, ELONGATED LOW LEVEL CIRCULATION (LLC). A 100308Z ASCAT-B PASS 
FURTHER OUTLINES THE STRUCTURE OF THE LLC STRETCHED FROM THE 
NORTHWEST TO THE SOUTHEAST WITH 20-25 KT WINDS IN THE NORTHERN SEMI-
CIRCLE. INVEST 91S IS IN A MARGINAL ENVIRONMENT FOR TROPICAL 
DEVELOPMENT WITH MINIMAL POLEWARD OUTFLOW AND HIGH (20-25KTS) 
VERTICAL WIND SHEAR WHICH IS SLIGHTLY OFFSET BY WARM (28-29C) SEA 
SURFACE TEMPERATURES. GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT 
INVEST 91S WILL TRACK EAST-SOUTHEAST OVER THE NEXT 24-48 HOURS WITH 
MINIMAL DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED 
AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE 
NEAR 1004 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.//
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