ABIO10 PGTW 211800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN
/OCEAN/211800Z-221800ZSEP2021//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/211821ZSEP2021//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT CANCELLATION//
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 90S) PREVIOUSLY LOCATED 
NEAR 10.2S 82.1E IS NOW LOCATED NEAR 10.3S 81.3E, APPROXIMATELY 560 
NM EAST-SOUTHEAST OF DIEGO GARCIA. ANIMATED ENHANCED INFRARED 
IMAGERY SHOWS BUILDING CONVECTION OBSCURING A LOW LEVEL CIRCULATION 
(LLC). DESPITE THE BUILDING CONVECTION,  A 1311Z SSMIS 91 GHZ IMAGE 
DEPICTS A DEGRADATION OF THE RAGGED LLC AND LOW LEVEL STRUCTURE. 
ENVIRONMENTAL ANALYSIS DEPICTS FAVORABLE CONDITIONS WITH LOW TO 
MODERATE (10-20 KTS) VERTICAL WIND SHEAR (VWS), WARM SST (27-28C), 
AND GOOD DIVERGENCE ALOFT. HOWEVER, GLOBAL MODELS ARE IN GOOD 
AGREEMENT THAT 90S WILL CONTINUE TO TRACK WEST SOUTH-WEST INTO AN 
AREA OF STRONG VWS (30-40 KTS) AS IT CONTINUES TO WEAKEN OVER THE 
NEXT 24 HOURS.  MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 
TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 
MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL 
CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM. SEE REF A 
(WTXS21 PGTW 201830) FOR FURTHER DETAILS.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.//
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