WTPN21 PGTW 120700
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
130 NM EITHER SIDE OF A LINE FROM 22.6N 136.1E TO 26.2N 139.3E
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 120600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 23.0N 136.3E. THE SYSTEM IS MOVING NORTH-NORTHEASTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 
21.9N 135.9E IS NOW LOCATED NEAR 23.0N 136.3E APPROXIMATELY 507 NM EAST-
SOUTHEAST OF KADENA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 
120404Z ASMR2 89GHZ MICROWAVE IMAGE DEPICT A DEEPENING AREA OF 
CONVECTION WITH FORMATIVE BANDING IN THE NORTHERN PERIPHERY OF THE 
RAPIDLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC). ENVIRONMENTAL 
ANALYSIS INDICATES A FAVORABLE ENVINROMENT FOR DEVELOPMENT WITH STRONG 
POLEWARD OUTFLOW, ENHANCED BY A TUTT-CELL SITUATED TO THE NORTHWEST, LOW 
VERTICAL WIND SHEAR (10-15KTS), AND VERY WARM (30-32C) SEA SURFACE 
TEMPERATURES. GLOBAL MODELS ARE IN AGREEMENT THAT 91W WILL GRADUALLY 
INTENSIFY AND CONTINUE TO TRACK NORTHWARD TOWARD MAINLAND JAPAN OVER THE 
NEXT 48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 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 
130700Z.
//
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