

WTPS21 PGTW 172130
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE FORMATION ALERT/172121ZMAR2006//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
200 NM EITHER SIDE OF A LINE FROM 16.4S 158.2E TO 18.8S 152.1E
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 30 TO 35 KNOTS. METSAT IM
AGERY AT 211800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.5S 157.9E. THE SYSTEM IS MOVING SOUTHWESTWARD AT 13
KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.5S
160.1E IS NOW LOCATED NEAR 16.5S 157.9E, APPROXIMATELY 700 NM EAST
OF CAIRNS, AUSTRALIA. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS A
INCREASED LOW TO MIDLEVEL ORGANIZATION AND FLARING CONVECTION OVER
THE PAST SIX HOURS. A RECENT 171828Z TRMM PASS REVEALS INCREASED LOW
LEVEL ORGANIZATION WITH STRONG BANDING CONVECTION ON THE SOUTHERN
PERIPHERAL. SUSTAINED DEEP CONVECTION IS CURRENTLY LIMITED BY A WEAK
UPPER LEVEL CYCLONE, WHICH HAS STARTED TO FILL OVER THE LAST 12
HOURS. UPPER LEVEL ANALYSIS ALSO INDICATES THE SYSTEM IS IN A WEAK
VERTICAL WIND SHEAR ENVIRONMENT. MAXIMUM SUSTAINED WINDS ARE ESTIM-
ATED AT 30 TO 35 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO
BE NEAR 1000 MB. BASED ON IMPROVED LOW LEVEL ORGANIZATION AND THE
STRENGTHENING UPPER LEVEL ANTICYCLONE, THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS UPGRADED TO GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
182130Z.//