WTPS21 PGTW 171500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
155 NM EITHER SIDE OF A LINE FROM 17.2S 159.0E TO 20.0S 169.1E
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 27 TO 32 KNOTS. METSAT
IMAGERY AT 171200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.3S 159.4E. THE SYSTEM IS MOVING EAST-SOUTHEASTWARD AT 10
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 
17.0S 158.4E IS NOW LOCATED NEAR 17.3S 159.4E APPROXIMATELY 499 NM 
NORTHWEST OF NOUMEA, NEW CALEDONIA. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY DISPLAYS A QUICKLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER 
(LLCC) WITH CURVED DEEP CONVECTIVE BANDING WRAPPING AROUND THE LLCC. AN 
171051Z ASCAT-B PARTIAL PASS PROVIDED GOOD CONFIDENCE TO THE INITIAL 
POSITION AND SHOWED THAT THE WIND FIELD IS STRENGTHENING, AT LEAST ON 
THE NORTHERN AND WESTERN SIDES OF THE CENTER, WITH 30-33 KNOT WINDS 
PRESENT ABOUT 75NM NORTH OF THE CENTER. ENVIRONMENTAL ANALYSIS REVEALS A 
FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH WARM (27-29C) SEA SURFACE 
TEMPERATURES, STRONG EQUATORWARD OUTFLOW, AND MARGINAL (15-25KT) VWS. 
MODEL GUIDANCE IS IN GOOD AGREEMENT THAT 91P WILL TRACK SOUTHEASTWARD 
ALONG THE SOUTHWEST SIDE OF A DEEP-LAYER NEAR-EQUATORIAL RIDGE (NER) 
THROUGH THE NEXT COUPLE OF DAYS. WHILE CURRENTLY A EXPERIENCING A FAIR 
AMOUNT OF AXIS TILT, THE MESOSCALE MODELS SUGGEST THE SYSTEM WILL 
QUICKLY SYMMETERIZE AND COMMENCE INTENSIFICATION SHORTLY THEREAFTER. THE 
LATEST COAMPS-TC DETERMINISTIC AND ENSEMBLE, AS WELL AS THE HWRF, 
INDICATE A MODERATE CHANCE OF RAPID INTENSIFICATION OVER THE NEXT 36 
HOURS AS THE SYSTEM TRACKS BETWEEN NEW CALEDONIA AND VANUATU.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 27 TO 32 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 999 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 
181500Z.
//
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