WTPN21 PGTW 050600 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 120 NM EITHER SIDE OF A LINE FROM 12.0N 134.7E TO 13.7N 132.2E 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 050600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 12.4N 134.4E. THE SYSTEM IS MOVING NORTHWESTWARD AT 05 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 98W) PREVIOUSLY LOCATED NEAR 10.9N 137.4E IS NOW LOCATED NEAR 12.4N 134.4E, APPROXIMATELY 280 NM NORTH-NORTHWEST OF YAP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS AN ELONGATED LOW-LEVEL CIRCULATION (LLC) WITH DEEP FLARING CONVECTION BUILDING ALONG THE EASTERN SEMI-CIRCLE. A 050017Z ASCAT-B BULLSEYE PASS REVEALS AN ELONGATED ASYMMETRIC CIRCULATION WITH A SWATH OF 20-25 KNOT WINDS IN THE NORTHERN PERIPHERY. INVEST 98W IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT, CHARACTERIZED BY NEAR RADIAL OUTFLOW AND LOW (10-15KT) VERTICAL WIND SHEAR. SEA SURFACE TEMPERATURES ARE CONDUCIVE AT A WARM 29-30C. GLOBAL MODELS ARE IN AGREEMENT THAT THE SYSTEM WILL GRADUALLY INTENSIFY AS IT TRACKS GENERALLY POLEWARD TO NORTHWESTWARD OVER THE NEXT 48 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 060600Z.// NNNN