WTXS21 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 11.3S 74.9E TO 15.3S 72.4E
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 23 TO 28 KNOTS. METSAT
IMAGERY AT 011200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 11.6S 74.8E. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99S) PREVIOUSLY LOCATED 10.8S 
75.0E IS NOW LOCATED NEAR 11.6S 74.8E, APPROXIMATELY 290 NM SOUTH-
SOUTHEASTWARD OF DIEGO GARCIA. ENHANCED INFRARED (EIR) SATELLITE IMAGERY 
DEPICTS 99S AS A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH 
STRONGER CONVECTION BUILDING NEAR THE CENTER. WITHIN THE LAST 24 HOURS, 
THE STRONGEST TURNING IS NEAR THE SOUTHEASTWARD SIDE OF THE LLCC BASED 
ON EARLIER SCATTEROMETER DATA. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE 
CONDITIONS FOR DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (15 KNOTS OR 
LESS), GOOD POLEWARD UPPER-LEVEL OUTFLOW ALOFT, AND WARM SEA SURFACE 
TEMPERATURES (29-30 C). GLOBAL AND ENSEMBLE MODELS ARE ON AGREEMENT WITH 
SWIFT DEVELOPMENT AND A STEADY SOUTHWESTWARD TRACK WITHIN THE NEXT 24 
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28 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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
021500Z.//
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