WTPN21 PGTW 220400 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91W)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 120 NM EITHER SIDE OF A LINE FROM 12.4N 142.1E TO 13.9N 140.1E 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 18 TO 23 KNOTS. METSAT IMAGERY AT 220000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 12.5N 141.9E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 06 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 12.2N 142.4E IS NOW LOCATED NEAR 12.5N 141.9E, APPROXIMATELY 173 NM WEST-SOUTHWEST OF GUAM. MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 22035Z METOP-C ASCAT PASS DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) OBSCURED BY FLARING, PATCHY CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE AREA FOR DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (10-15KTS), GOOD EQUATORWARD OUTFLOW, AND A WARM SEA SURFACE TEMPERATURE (29-30C). GLOBAL DETERMINISTIC AND ENSEMBLE MODELS DEPICT FORMATION OF A TROPICAL DEPRESSION WITHIN 24 TO 48 HOURS AS THE SYSTEM TRACKS NORTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 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 230400Z.// NNNN WTPN21 PGTW 220400 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91W)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 120 NM EITHER SIDE OF A LINE FROM 12.4N 142.1E TO 13.9N 140.1E 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 18 TO 23 KNOTS. METSAT IMAGERY AT 220000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 12.5N 141.9E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 06 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 12.2N 142.4E IS NOW LOCATED NEAR 12.5N 141.9E, APPROXIMATELY 173 NM WEST-SOUTHWEST OF GUAM. MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 220035Z METOP-C ASCAT PASS DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) OBSCURED BY FLARING, PATCHY CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE AREA FOR DEVELOPMENT WITH LOW VERTICAL WIND SHEAR (10-15KTS), GOOD EQUATORWARD OUTFLOW, AND A WARM SEA SURFACE TEMPERATURE (29-30C). GLOBAL DETERMINISTIC AND ENSEMBLE MODELS DEPICT FORMATION OF A TROPICAL DEPRESSION WITHIN 24 TO 48 HOURS AS THE SYSTEM TRACKS NORTHWESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 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 230400Z.// NNNN