WTPS21 PGTW 041130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91P)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 12.4S 171.0E TO 16.7S 172.7E
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 28 TO 33 KNOTS. METSAT
IMAGERY AT 040600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.7S 171.2E. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 04
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91P) PERVIOUSLY LOCATED NEAR 
12.3S 171.3E, IS NOW LOCATED NEAR 12.7S 171.2E, APPROXIMATELY 345 NM 
NORTH-NORTHEAST OF PORT VILA. MULTISPECTRAL SATELLITE IMAGERY (MSI) 
REVEALS A BROAD LOW LEVEL CIRCULATION CENTER (LLCC) WITH AN ELONGATED 
BUT SLOWLY CONSOLIDATING CENTER AND RECENTLY DEVELOPING DEEP CONVECTION 
ALONG THE EASTERN SIDE OF THE CIRCULATION. A 040959Z ASCAT PASS SHOWS A 
DEFINED CIRCULATION WITH STRONGER WINDS OF 25-30 KNOTS WRAPPING AROUND 
THE SOUTH AND EASTERN SIDE OF THE CIRCULATION, WITH A FEW ISOLATED 
PATCHES OF 35 KNOTS EMBEDDED UNDER THE DEEPEST CONVECTIVE CELLS. 
ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS FOR DEVELOPMENT WITH 
LOW TO MODERATE VERTICAL WIND SHEAR (15-20 KNOTS), GOOD DIFFLUENT 
OUTFLOW ALOFT, AND WARM SEA SURFACE TEMPERATURES (29-30 C). GLOBAL 
MODELS ARE IN FAIR AGREEMENT THAT INVEST 91P WILL CONTINUE TO HAVE 
STEADY DEVELOPMENT AND A SOUTHWARD TRACK OVER THE NEXT 12 TO 24 HOURS. 
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 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 
051130Z.//
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