WTPS21 PGTW 100200
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
TROPICAL CYCLONE FORMATION ALERTRMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 18.3S 155.7W TO 20.6S 161.5W
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 25 TO 30 KNOTS. METSAT IM-
AGERY AT 100130Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 18.7S 156.4W. THE SYSTEM IS MOVING WEST-SOUTHWESTWARD AT 04
KNOTS.
2. REMARKS: AN AREA OF CONVECTION HAS PERSISTED NEAR 18.7S 156.4W,
APPROXIMATELY 415 NM WEST OF TAHITI. RECENT ANIMATED MULTISPECTRAL
IMAGERY SHOWS A WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC)
WITH FORMATIVE CONVECTIVE BANDING WRAPPING INTO THE CENTER. THIS
LLCC IS CONFIRMED BY A 091715Z QUIKSCAT PASS SHOWING WINDS OF 25 TO
30 KNOTS NEAR THE CENTER. AN ANTI-CYLCONE ALOFT, AND WEAK UPPER-
LEVEL TROUGHING TO THE SOUTHEAST OF THE DISTURBANCE, ARE PROVIDING
AMPLE OUTFLOW FOR DEVELOPMENT. THE SYSTEM LIES IN A REGION OF WEAK
TO MODERATE VERTICAL WIND SHEAR, WARM SST (>26C) AND SIGNIFICANT
OCEAN HEAT CONTENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT
25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR
1001 MB. DUE TO THE FAVORABLE SURFACE CONDITON AS WELL AS GOOD
CONDITIONS ALOFT, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT
TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
100200Z.