WTPN21 PGTW 210800
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
130 NM EITHER SIDE OF A LINE FROM 16.2N 143.7E TO 19.2N 138.3E
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 210700Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.5N 143.4E. THE SYSTEM IS MOVING NORTHWESTWARD AT 11
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED 
NEAR 15.3N 144.4E IS NOW LOCATED NEAR 16.5N 143.4E, APPROXIMATELY 202 
NM NORTH-NORTHWEST OF GUAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY 
AND A 210355Z AMSR2 89GHZ SATELLITE IMAGERY DEPICT AN AREA OF 
PERSISTENT DEEP CONVECTION, WITH FRAGMENTED FORMATIVE BANDING SLOWLY 
WRAPPING AROUND THE CIRCULATION. ANALYSIS REVEALS THAT 90W IS IN AN 
OVERALL FAVORABLE ENVIRONMENT FOR FURTHER DEVELOPMENT WITH GOOD 
EQUATORWARD OUTFLOW ALOFT AND WARM SEA SURFACE TEMPERATURES (30C) 
OFFSET BY MODERATE (15-20 KTS) VERTICAL WIND SHEAR. GLOBAL MODELS ARE 
IN GOOD AGREEMENT THAT 90W WILL GENERALLY TRACK NORTH-NORTHWESTWARD AS 
THE SYSTEM GRADUALLY INTENSIFIES OVER THE NEXT 24-48 HOURS. MAXIMUM 
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA 
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1003 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 
220800Z.//
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