WTXS22 PGTW 040800 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90S)// REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/031351Z APR 21// AMPN/REF A IS A TROPICAL CYCLONE FORMATION ALERT.// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 120 NM EITHER SIDE OF A LINE FROM 13.4S 104.8E TO 15.8S 107.2E 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 25 TO 30 KNOTS. METSAT IMAGERY AT 040600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 13.8S 105.2E. THE SYSTEM IS MOVING SOUTH-SOUTHEASTWARD AT 12 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR 10.8S 102.9E IS NOW LOCATED NEAR 13.8S 105.2E, APPROXIMATELY 203 NM SOUTH OF CHRISTMAS ISLAND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 040634Z AMSR2 GW1 89GHZ MICROWAVE IMAGE DEPICT PERSISTENT DEEP CONVECTION OVERHEAD A SLIGHTLY ELONGATED LOW LEVEL CIRCULATION CENTER (LLCC) WITH DEVELOPING DEEP CONVECTIVE BANDING TIGHTLY WRAPPING IN FROM THE EAST. THE OVERALL CONVECTIVE STRUCTURE REMAINS VERY ASYMMETRIC WITH VERY LITTLE CONVECTIVE SIGNATURE IN THE WESTERN SEMICIRCLE. A 040246Z METOP-C ASCAT PASS REVEALS A HIGHLY ASYMMETRIC WIND FIELD WITH ENHANCED (25 TO 30 KNOT) WINDS TURNING AROUND THE SOUTHERN EDGE OF THE ELONGATED LLCC AND WEAKER (5 TO 10 KNOT) WINDS CONSIGNED TO THE NORTH. 90S IS CURRENTLY IN A FAVORABLE ENVIRONMENT WITH WARM (30 CELSIUS) SEA SURFACE TEMPERATURES, LOW (5 TO 10 KNOTS) VERTICAL WIND SHEAR, AND EXCELLENT POLEWARD OUTFLOW; HOWEVER, THE HIGH TRACK SPEEDS MAY BE SLIGHTLY OFFSETTING THE ENVIRONMENTAL FACTORS. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 90S WILL REMAIN ELONGATED AND ASYMMETRIC AS IT TRACKS SOUTHEAST AND INTENSIFIES, REACHING WARNING THRESHOLD WITHIN 36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 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 050800Z. 4. SEE REF A (WTXS21 PGTW 031400) FOR DETAILS ON A TROPICAL CYCLONE FORMATION ALERT LOCATED NEAR 10.7S 123.8E.// NNNN