WTPN21 PGTW 240800
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
160 NM EITHER SIDE OF A LINE FROM 14.9N 113.2E TO 15.6N 107.4E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 240600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 14.8N 112.4E. THE SYSTEM IS MOVING WESTWARD AT 12 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 
14.9N 113.0E IS NOW LOCATED NEAR 14.8N 112.4E, APPROXIMATELY 450 NM 
SOUTH OF HONG KONG. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 
240617Z 88.2 GHZ ATMS MICROWAVE IMAGE DEPICT A BROAD AREA OF ELONGATED 
LOW LEVEL TURNING OF WEST-SOUTHWEST TO EAST-NORTHEAST ORIENTATION WITH 
DEEP CONVECTION ALONG THE WESTERN PERIPHERY. ENVIRONMENTAL ANALYSIS 
INDICATES THAT 91W IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH 
GOOD EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, 
AND WARM (30-31 C) SST. GLOBAL NUMERICAL DETERMINISTIC AND ENSEMBLE 
MODELS ARE IN AGREEMENT THAT 91W WILL TRACK SLOWLY WESTWARD AND 
CONTINUE TO DEVELOP OVER THE NEXT 12-24 HOURS.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 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 
250800Z.
//
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