WTXS21 PGTW 280900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98S) REISSUED//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/270851ZMAR21//
AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 11.9S 68.0E TO 8.7S 72.1E WITHIN 
THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF 
NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA 
ARE ESTIMATED TO BE 28 TO 33 KNOTS. METSAT IMAGERY AT 280830Z 
INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 11.7S 68.3E. THE 
SYSTEM IS MOVING EAST-SOUTHEASTWARD AT 09 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 98S) PREVIOUSLY LOCATED 
NEAR 10.4S 66.0E IS NOW LOCATED NEAR 11.7S 68.3E, APPROXIMATELY 356
NM SOUTHWEST OF DIEGO GARCIA. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY SHOWS THAT A WELL-DEFINED LOW-LEVEL CIRCULATION (LLC) 
REMAINS CENTERED NEAR THE NORTHEASTERN EDGE OF A RAGGED AREA OF DEEP 
CONVECTION, WHICH HAS PULSED IN DISORGANIZED FASHION DURING THE PAST 
24 HOURS, AND HAS DEGRADED IN PRESENTATION. THE LLC REMAINS 
DECOUPLED FROM THE MID-LEVEL CIRCULATION TO ITS SOUTHWEST DUE TO 
NORTHEASTERLY VERTICAL WIND SHEAR (VWS) OF 15-20 KTS, WHICH IS NOW 
INCREASING DUE TO OUTFLOW FROM A LARGE AREA OF CONVECTION WEST OF 
THE MALDIVES. A 280419Z ASCAT-B PASS INDICATES THAT THE VORTEX IS 
LESS STOUT THAN 24 HOURS AGO, WITH THE MAX WIND BAND NO LONGER 
WRAPPING AROUND THE NORTH SIDE. OVERALL, THE SYSTEM'S ENVIRONMENT IS 
MARGINALLY FAVORABLE AND BECOMING LESS HOSPITABLE, DUE TO THE 
AFOREMENTIONED INCREASING VWS AND A DRYING AIR MASS TO THE NORTH OF 
THE CIRCULATION. HOWEVER, NUMERICAL MODELS CONTINUE TO INDICATE THAT 
SLIGHT INTENSIFICATION INTO A SHORT-LIVED SIGNIFICANT TROPICAL 
CYCLONE IS POSSIBLE IN THE NEAR TERM DUE TO THE COMPACT NATURE OF 
THE VORTEX AND WARM UNDERLYING SEA SURFACE TEMPERATURES OF 29C. 
INVEST 98S IS EXPECTED TO SOON TURN EASTWARD AND THEN NORTHEASTWARD, 
TOWARD THE VICINITY OF DIEGO GARCIA, FOLLOWING THE BELT OF STRONG 
LOW TO MID-LEVEL WESTERLY FLOW ALONG THE SOUTHERN PERIPHERY OF A 
BROAD CIRCULATION WEST OF THE MALDIVES. 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 REMAINS HIGH. 
THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
290900Z.//
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