WTXS21 PGTW 050730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
095 NM EITHER SIDE OF A LINE FROM 13.4S 62.1E TO 16.0S 60.3E
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 28 TO 33 KNOTS. METSAT
IMAGERY AT 050600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 13.5S 62.0E. THE SYSTEM IS MOVING SOUTH-SOUTHWESTWARD AT 07
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR 
12.7S 62.5E IS NOW LOCATED NEAR 13.5S 62.0E, APPROXIMATELY 477 NM NORTH-
NORTHEAST OF MAURITIUS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND 
A 050448Z METOP-C ASCAT PASS REVEALED A GRADUALLY CONSOLIDATING, FULLY 
EXPOSED LOW-LEVEL CIRCULATION WITH ELEVATED SURFACE WINDS LOCATED IN 
CLOSE PROXIMITY TO FLARING ISOLATED CONVECTIVE STRUCTURES THROUGHOUT THE 
WESTERN AND NORTHERN QUADRANTS. ENVIRONMENTAL ANALYSIS SHOWS MARGINALLY 
FAVORABLE CONDITIONS WITH WARM SEA SURFACE TEMPERATURES OF 28-29 C, GOOD 
EQUATORWARD OUTFLOW, OFFSET BY 20-25 KTS OF SOUTHEASTERLY VERTICAL WIND 
SHEAR. GLOBAL DETERMINISTIC AND ENSEMBLE MODELS ARE IN A GOOD AGREEMENT 
ON STEADY INTENSIFICATION, ALTHOUGH ENSEMBLES SHOW SLIGHT DISAGREEMENT 
ON THE TRACK AFTER 72 HOURS. THE GFS ENSEMBLE CHARACTERIZES A WESTWARD 
TURN TOWARDS MADAGASCAR INTO TAU 72 WHILE THE ECMWF ENSEMBLE ILLUSTRATES 
A STEADY TRACK SOUTHWESTWARD INTO TAU 72, WITH A WESTWARD TRACK 
THEREAFTER. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 TO 33 
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 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 
060730Z.//
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