WTPN21 PGTW 050200
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 21.7N 131.4E TO 29.7N 138.2E
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 17 TO 22 KNOTS. METSAT
IMAGERY AT 050000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 21.9N 131.7E. THE SYSTEM IS MOVING NORTHEASTWARD AT 09
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 
21.1N 130.3E IS NOW LOCATED NEAR 21.9N 131.7E, APPROXIMATELY 244 NM 
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY  AND A 042210Z SSMIS 91 GHZ IMAGE DEPICTS A PARTLY OBSCURED LLCC 
WITH BUILDING CONVECTION TO THE SOUTHWEST AND LOWER LEVEL CLOUDS 
WRAPPING AROUND THE LLCC. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE 
ENVIRONMENT WITH DUAL CHANNEL OUTFLOW TO THE NORTH AND SOUTH, LOW 
VERTICAL WINDSHEAR(5-10KTS) AND WARM SEA SURFACE TEMPERATURES (29-30C). 
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 99W WILL TRACK NORTH-NORTHEAST 
AND CONTINUE TO DEVELOP OVER THE NEXT 12-36 HOURS. MAXIMUM SUSTAINED 
SURFACE WINDS ARE ESTIMATED AT 17 TO 22 KNOTS. MINIMUM SEA LEVEL 
PRESSURE IS ESTIMATED TO BE NEAR 1006 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 
060200Z.
//
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