ABIO10 PGTW 181800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE INDIAN 
OCEAN/181800Z-191800ZMAR2025//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/181751ZMAR2025//
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 91S) PREVIOUSLY LOCATED NEAR 
12.8S 98.1E IS NOW LOCATED NEAR 13.1S 96.6E, APPROXIMATELY 57.2 NM 
SOUTH-SOUTHWEST OF COCOS ISLANDS. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY FROM HIMAWARI-9 DEPICTS CURVED DEEP CONVECTIVE 
BANDING OVER A CONSOLIDATING LLCC. A 1532Z AMSU-B MICROWAVE IMAGE SHOWS 
THAT THE VORTEX REMAINS SLIGHTLY TILTED WESTWARD WITH HEIGHT, BUT 
CONVECTIVE ORGANIZATION HAS IMPROVED IN THE WESTERN SEMICIRCLE OVER THE 
PAST SIX HOURS.  A 181730Z SURFACE OBSERVATION FROM COCOS ISLAND 
INTERNATIONAL AIRPORT SHOWS NORTHWESTERLY 26 KNOT WINDS WITH GUSTS OF 
37 KNOTS AND AN MSLP VALUE OF 1004MB. ENVIRONMENTAL ANALYSIS INDICATES 
THAT INVEST 91S IS IN A FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT 
DUE TO WARM (29-30C) SEA SURFACE TEMPERATURES, MODERATE (15-20 KNOTS) 
VERTICAL WIND SHEAR, AND STRONG POLEWARD OUTFLOW ALOFT. GLOBAL MODELS 
ARE IN AGREEMENT THAT 91S WILL STEADILY DEVELOP AND TRANSIT TO THE 
SOUTHWEST DURING THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE 
ESTIMATED AT 28 TO 33 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 
A (WTXS21 PGTW 181800) FOR FURTHER DETAILS.
      (2) NO OTHER SUSPECT AREAS.
   C. SUBTROPICAL SYSTEM SUMMARY: NONE.
//
NNNN