WTPN21 PGTW 181930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 16W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
185 NM EITHER SIDE OF A LINE FROM 15.3N 137.4E TO 20.2N 130.1E
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 081800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 15.6N 137.1E. THE SYSTEM IS MOVING NORTHWESTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 16W) PREVIOUSLY LOCATED 
NEAR 14.3N 138.1E IS NOW LOCATED NEAR 15.6N 137.1E, APPROXIMATELY 
830 NM SOUTHEAST OF KADENA AB. A 181627Z ASMR2 89GHZ PASS REVEALS 
FLARING CONVECTION TO THE SOUTH-SOUTHWEST PERIPHERY AS WELL AS 
BANDING INTO A LOW LEVEL CIRCULATION (LLC). ENVIRONMENTAL ANALYSIS 
INDICATES A FAVORABLE ENVIRONMENT CHARACTERIZED BY RADIAL OUTFLOW, 
LOW (10-15KT) VERTICAL WIND SHEAR (VWS), AND VERY WARM (30-31C) SEA 
SURFACE TEMPERATURES (SST). GLOBAL NUMERICAL MODELS GENERALLY AGREE 
THAT INVEST 16W WILL TRACK NORTHWESTWARD OVER THE NEXT 48 HOURS. 
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15-20 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 
191930Z.//
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