WTPN21 PGTW 152030
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
140 NM EITHER SIDE OF A LINE FROM 17.4N 132.2E TO 21.5N 131.3E
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 15 TO 20 KNOTS. METSAT
IMAGERY AT 151800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.4N 132.2E. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 98W) PREVIOUSLY LOCATED 
NEAR 17.5N 137.5E IS NOW LOCATED NEAR 17.4N 132.2E, APPROXIMATELY 
593 NM SOUTH-SOUTHEAST OF KADENA, OKINAWA, JAPAN. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY (MSI), A 151639Z AMSR2 36GHZ, AND AN 
ASMR2 89GHZ MICROWAVE IMAGE DEPICT A BROAD ASYMMETRICAL CONVECTIVE 
ZONE ON THE EASTERN BOUNDARY OF THE LOW LEVEL CIRCULATION (LLC). 
DESPITE THE ASYMMETRICAL CONVECTIVE ZONE, 98W WILL CONSOLIDATE AND 
INTENSIFY. ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR 
DEVELOPMENT WITH GOOD OUTFLOW ALOFT, WARM (30-31C) SEA SURFACE 
TEMPERATURES, AND LOW (05-10 KTS) VERTICAL WIND SHEAR (VWS). IN THE 
UPPER LEVELS, THE PATTERN IS COMPLEX WITH MULTIPLE STEERING FORCES; 
THE FAVORABLE POLEWARD POSITIONING OF AN UPPER LEVEL LOW WILL 
ENHANCE OUTFLOW AND DIVERGENCE ALOFT, WHILE IN THE LOWER LEVELS A 
STRONG WESTERLY COMPONENT WILL ENHANCE CONSOLIDATION. HOWEVER, THERE 
IS A STRONG DISPARITY AMONGST THE NUMERICAL MODELS OVER THE TRACK 
AND INTENSIFICATION TIMELINE. GLOBAL AND ENSEMBLE GFS HAS 98W 
INTENSIFYING WITHIN 18-36 HOURS AND TRACKING WEST-NORTHWEST AT A 
HIGHER SPEED OF ADVANCE TO THE RYUKYU ISLANDS, WHILE GLOBAL AND 
ENSEMBLE ECMWF HAVE A GRADUAL INTENSIFICATION PATTERN WITH A SLOWER 
SPEED OF ADVANCE TO KYUSHU, JAPAN. CURRENT ANALYSIS INDICATES THAT 
ECMWF HAS BEEN THE MORE CONSISTENT MODEL AT HANDLING THE 
COMPLEXITIES OF 98W OVER THE LAST 48 HOURS. MAXIMUM SUSTAINED 
SURFACE WINDS ARE ESTIMATED AT 15 TO 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 UPGRADED TO HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
162030Z.
//
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