SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)// MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// WTPN21 PGTW 300600// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 140 NM EITHER SIDE OF A LINE FROM 17.9N 131.6E TO 21.8N 130.5E 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 18 TO 23 KNOTS. METSAT IMAGERY AT 300000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 18.2N 131.4E. THE SYSTEM IS MOVING NORTHEASTWARD AT 06 KNOTS. 2. REMARKS:AN AREA OF CONVECTION (INVEST 98W) HAS PERSISTED NEAR 18.2N 131.4E, APPROXIMATELY 530NM SOUTH-SOUTHEAST OF KADENA, JAPAN. ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN INCREASINGLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH ILL DEFINED CONVECTIVE BANDING TO THE NORTH AND SOUTHWEST OF THE SYSTEM. A TUTT CELL TO THE NORTHWEST OF 98W HAS AIDED IN ITS DEVELOPMENT WITH AN INCREASE TO THE UPPER LEVEL OUTFLOW. INTENSITY GUIDANCE SHOWS THE SYSTEM TRACKING NORTHWEST AND BECOMING TD STRENGTH WITHIN THE NEXT 12-24 HOURS AS IT MOVES NORTH-NORTHWEST TOWARDS KADENA. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT DEFINED BY; MODERATE EQUATORWARD OUTFLOW ALOFT, LOW (10-15KT) VERTICAL WIND SHEAR, AND WARM (30C) SEA SURFACE TEMPERATURES. GLOBAL DETERMINISTIC AND ENSEMBLE MODELS CONCUR THAT 98W WILL FURTHER DEVELOP ALONG ITS NORTH-NORTHWESTWARD TRACK OVER THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS.MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 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 010600Z. NNNN