ABIO10 PGTW 270930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN 
OCEAN REISSUED/270930Z-271800ZMAR2021//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/270851ZMAR21//
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 95S) PREVIOUSLY LOCATED 
NEAR 10.8S 90.8E HAS DISSIPATED AND IS NO LONGER SUSPECT FOR THE 
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE IN THE NEXT 24 HOURS.
      (2) THE AREA OF CONVECTION (INVEST 98S) PREVIOUSLY LOCATED 
NEAR 9.9S 64.9E IS NOW LOCATED NEAR 10.2S 65.6E, APPROXIMATELY 439 
NM WEST-SOUTHWEST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY DEPICTS A WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) 
LOCATED NEAR THE NORTHEAST EDGE OF A MASS OF CONVECTION THAT HAS 
EXHIBITED PULSING BURSTS DURING THE PAST 6 HOURS. SATELLITE IMAGERY 
INDICATES THAT THE MID-LEVEL CIRCULATION CENTER IS DISPLACED WEST OF 
THE LLCC AS A RESULT OF 10-15 KTS OF EASTERLY VERTICAL WIND SHEAR, 
AND THE LLCC IS PARTIALLY EXPOSED ON THE NORTHEAST SIDE. HOWEVER, A 
270533Z ASCAT-C IMAGE REVEALS A COMPACT CIRCULATION THAT HAS SEEN 
ITS RADIUS OF MAXIMUM WIND CONTRACT SUBSTANTIALLY TO AROUND 20 NM 
DURING THE PAST 12 HOURS, WITH A BAND OF 30 KT WINDS ENCOMPASSING 
THE ENTIRE NORTHWESTERN SEMICIRCLE. HEALTHY UPPER-LEVEL OUTFLOW IS 
OBSERVED IN ALL QUADRANTS EXCEPT NORTHEAST. INVEST 98S IS LOCATED IN 
A MOSTLY FAVORABLE ENVIRONMENT WITH SEA SURFACE TEMPERATURES AROUND 
29C AND LIGHT-MODERATE VERTICAL WIND SHEAR. WATER VAPOR SATELLITE 
IMAGERY AND PRECIPITABLE WATER DATA INDICATE A BAND OF DRY AIR 
LOCATED ABOUT 200 NM SOUTHWEST OF THE SYSTEM, BUT DOES NOT APPEAR TO 
BE WRAPPING INTO THE CIRCULATION AT PRESENT. NUMERICAL MODELS HAVE 
MIXED OPINIONS ON DEVELOPMENT, WITH MOST SHOWING ONLY SLIGHT 
INTENSIFICATION OF 98S IN THE SHORT TERM. HOWEVER, MOST MODELS 
DEPICT 98S WITH A BROADER AND WEAKER CIRCULATION THAN IS BEING 
OBSERVED, SUGGESTING THAT DEVELOPMENT CHANCES ARE HIGHER. INVEST 98S 
IS EXPECTED TO TRACK EAST-SOUTHEASTWARD AND THEN TURN EASTWARD UNDER 
THE INFLUENCE OF A WESTERLY WIND BAND TO ITS NORTH. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1002 MB. THE POTENTIAL FOR 
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 
HOURS IS UPGRADED TO HIGH. SEE REF A (WTXS21 PGTW 270900) 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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