Indian Ocean Tropical Cyclone Tracking

ABIO10 PGTW 090100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN OCEAN 
REISSUED/090100Z-091800ZDEC2024//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/090051ZDEC2024//
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 92S) PREVIOUSLY LOCATED NEAR 
10.9S 67.9E IS NOW LOCATED NEAR 11.5S 64.9E, APPROXIMATELY 675 NM 
NORTHEAST OF MAURITIUS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY DEPICTS INVEST 92S WITH A PARTIALLY OBSCURED LLCC AND 
PERSISTENT CONVECTION BEING SHEARED FROM THE EAST, THOUGH THE LLCC HAS 
BEEN STEADILY MOVING CLOSER TO THE CONVECTIVE MASS. A 082041Z AMSR2 
89GHZ MICROWAVE IMAGE SHOWS WELL-DEFINED LOW-LEVEL BANDING FEATURES 
WRAPPING INTO THE LLCC, WHICH REMAINS EAST OF THE DEEPEST CONVECTION. 
92S IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT 
WITH GOOD POLEWARD AND EQUATORWARD UPPER-LEVEL OUTFLOW AND WARM SEA 
SURFACE TEMPERATURES OF 28-29C OFFSET BY MODERATE TO HIGH VERTICAL 
WIND SHEAR OF 20-25 KT. HOWEVER, CIMSS ATMOSPHERIC MOTION VECTOR (AMV) 
ANALYSIS SHOWS THE UPPER-LEVEL WINDS ARE SPLITTING TO THE EAST OF 92S, 
AND LOCALIZED SHEAR NEAR THE CENTER IS LIKELY LOWER THAN THE 
ENVIRONMENTAL SHEAR. LASTLY, GLOBAL DETERMINISTIC MODELS ARE IN 
AGREEMENT THAT INVEST 92S WILL CONTINUE TO CONSOLIDATE OVER THE NEXT 
24HRS. MESOSCALE INTENSITY GUIDANCE INDICATES THAT 92S WILL QUICKLY 
INTENSIFY AND REACH WARNING THRESHOLD WITHIN THE NEXT 18 TO 24 HOURS. 
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 090100) 
FOR FURTHER DETAILS.
      (2) THE AREA OF CONVECTION (INVEST 91S) PREVIOUSLY LOCATED NEAR 
8.5S 100.2E IS NOW LOCATED NEAR 10.1S 98.4E, APPROXIMATELY 155 NM 
NORTHEAST OF COCOS ISLANDS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY CONTINUES TO DEPICT INVEST 91S WITH A FULLY EXPOSED LLCC WITH 
PERSISTENT CONVECTION SHEARED TO THE WEST OF THE LLCC. A 081413Z ASCAT 
METOP-B 50 KM PARTIAL PASS REVEALS 15-20 KT TO THE NORTH AND SOUTH OF 
THE LLCC. AS FOR THE ENVIRONMENTAL ANALYSIS, 91S IS IN A MARGINAL 
ENVIRONMENT FOR FURTHER DEVELOPMENT WITH WARM SEA SURFACE TEMPERATURES 
OF 29-30C OFFSET BY WEAK POLEWARD UPPER-LEVEL OUTFLOW AND HIGH 
VERTICAL WIND SHEAR OF 25-30 KT. LASTLY, GLOBAL DETERMINISTIC MODELS 
CONTINUE TO SHOW THE SYSTEM REMAINING NEARLY QUASI-STATIONARY, WHILE 
BACKING OFF ON THE DEVELOPMENT ODDS FOR 91S. GLOBAL DETERMINISTIC 
GUIDANCE NOW SUGGESTS THE CIRCULATION IS UNLIKELY TO DEVELOP INTO A 
TROPICAL CYCLONE WITHIN THE NEXT 24 TO 48 HOURS, AND ENSEMBLE GUIDANCE 
CONTINUES TO SHOW A DOWNWARD TREND IN THE PROBABILITIES FOR 
DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28 
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 LOW.
      (3) AN AREA OF CONVECTION (INVEST 93S) HAS PERSISTED NEAR 16.5S 
117.6E, APPROXIMATELY 397 NM NORTH-NORTHEAST OF LEARMONTH. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY DEPICTS INVEST 93S WITH A BROAD LOW 
LEVEL CIRCULATION (LLC) WITH FLARING, PERSISTENT CONVECTION. A 082220Z 
SSMIS 91GHZ MICROWAVE IMAGE REVEALS FRAGMENTED, FORMATIVE BANDING 
ALONG THE SOUTHERN PERIPHERY OF THE CIRCULATION, WITH LOW-LEVEL 
BANDING FEATURES EVIDENT IN THE NORTHERN PORTION OF THE CIRCULATION. 
93S IS IN A MARGINALLY FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT 
WITH GOOD POLEWARD UPPER-LEVEL OUTFLOW AND WARM SEA SURFACE 
TEMPERATURES OF 28-30C OFFSET BY A TIGHT GRADIENT OF 10-30 KT VERTICAL 
WIND SHEAR. LASTLY, GLOBAL MODELS INDICATE THAT INVEST 93S WILL 
CONTINUE TO CONSOLIDATE OVER THE NEXT 24 HOURS, WITH NAVGEM BEING THE 
MOST AGGRESSIVE, REACHING WARNING THRESHOLD BY 48 HOURS. AS FOR THE 
ENSEMBLE GUIDANCE, GEFS AND ECENS ARE SPLIT WITH ECENS BEING THE MOST 
AGGRESSIVE COMPARED TO GEFS WHICH SHOWS ONLY VERY FEW MEMBERS 
FORECASTING DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED 
AT 18 TO 23 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 LOW.
      (4) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
3. JUSTIFICATION FOR REISSUE: UPGRADED AREA IN PARA. 2.B.(1) TO HIGH. 
ADDED LOW AREA IN PARA. 2.B.(3).//
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