AN AREA OF CONVECTION (INVEST 90S) HAS PERSISTED NEAR 11.6S
66.7E, APPROXIMATELY 426 NM SOUTHWEST OF DIEGO GARCIA. ENHANCED
INFRARED SATELLITE IMAGERY (EIR) REVEALS A POORLY ORGANIZED LOW LEVEL
CIRCULATION CENTER (LLCC) WITH FLARING CONVECTION OFFSET TO THE
NORTHWEST. ENVIRONMENTAL ANALYSIS REVEALS MODERATE TO FAVORABLE
CONDITIONS FOR DEVELOPMENT WITH LOW TO MODERATE VERTICAL WIND SHEAR
(15-20 KNOTS), GOOD UPPER-LEVEL POLEWARD OUTFLOW, AND WARM (28-29C)
SEA SURFACE TEMPERATURES. DETERMINISTIC MODELS SUCH AS GFS AND ECMWF
SHOW STEADY DEVELOPMENT OF 90S INTO A TROPICAL CYCLONE WITHIN ABOUT 72
HOURS. FURTHERMORE, ENSEMBLE MODELS FAVOR DEVELOPMENT AS INVEST 90S
TRACKS GENERALLY SOUTH-SOUTHWESTWARD OVER THE NEXT FEW DAYS. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
IS LOW.
THE AREA OF CONVECTION (INVEST 90S) PREVIOUSLY LOCATED NEAR
11.3S 63.7E IS NOW LOCATED NEAR 11.6S 63.4E, APPROXIMATELY 625 NM
NORTH-NORTHEAST OF MAURITIUS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) REVEALS AN EXPOSED LOW-LEVEL CIRCULATION CENTER THAT IS
CONTINUING TO CONSOLIDATE. DEEP CONVECTION CONTINUES TO BUILD AROUND
THE CENTER AS EVIDENCED BY SIGNIFICANTLY COOLED CLOUD TOP TEMPERATURES
OVER THE PAST SIX HOURS. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE
CONDITIONS FOR DEVELOPMENT WITH MODERATE VERTICAL WIND SHEAR (15-20
KNOTS), GOOD UPPER-LEVEL EQUATORWARD OUTFLOW, AND WARM (28-29 C) SEA
SURFACE TEMPERATURES. GLOBAL MODELS AGREE ON A SLOW SOUTHWARD TRACK
AND STEADY DEVELOPMENT OVER THE NEXT 48 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 23 TO 27 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS
REMAINS MEDIUM.
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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