WTPS21 PGTW 180630 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91P) CANCELLATION// REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/170751ZMAY2022// 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 13.7S 171.8E TO 15.4S 170.0E 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 19 TO 24 KNOTS. METSAT IMAGERY AT 170600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 13.8S 171.9E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 04 KNOTS. 2. REMARKS: THIS CANCELS REF A (WTPS21 PGTW 170800). THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 13.7S 171.E IS NOW LOCATED NEAR 15.3S 169.7E, APPROXIMATELY 156 NM NORTH-NORTHEAST OF PORT VILA, VANUATU . ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LOW-LEVEL CIRCULATION (LLC) THAT HAS DECOUPLED FROM THE CENTRAL DEEP OVERCAST (CDO) AND DRIFTED MORE WESTWARD AND AWAY FROM ITS ORIGINAL SOUTHWESTWARD TRACK. THE CDO HAS BECOME MORE SHALLOW AND DISORGANIZED, INCLUDING ITS MAIN FORMATIVE RAIN BAND TRAILING FROM THE NORTHERN PERIPHERY. UPPER-LEVEL ANALYSIS REVEALS THE ENVIRONMENT HAS BECOME UNFAVORABLE WITH LIGHT TO MODERATE (10-20 KNOTS) VERTICAL WIND SHEAR (VWS) DIRECTLY OVER THE LLC BUT STARTING FROM 60NM TO THE SOUTH AND POLEWARD AND OVER THE CDO, VWS BECOMES HIGH (25KTS+). THE INCREASING VWS HAS NOW OFFSET THE VERY WARM (29-30C) SEA SURFACE TEMPERATURE AND STRONG POLEWARD OUTFLOW. GLOBAL DYNAMIC MODELS CONTINUE TO INDICATE INTENSIFICATION OVER THE NEXT 24-36 HOURS, HOWEVER, UNDER THE ASSUMPTION THAT THE SYSTEM RESUMES A SOUTHWESTWARD TRACK. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. IN VIEW OF THE SIGNIFICANT DEGRADATION OF THE SYSTEM AND THE CHANGE IN TRACK, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS DOWNGRADED TO MEDIUM.// NNNN