WTPS21 PGTW 100530
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
150 NM EITHER SIDE OF A LINE FROM 12.1S 172.3W TO 13.1S 167.9W
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 25 TO 30 KNOTS. METSAT
IMAGERY AND SYNOPTIC DATA AT 100500Z INDICATE THAT A CIRCULATION
CENTER IS LOCATED NEAR 12.6S 171.4W.  THE SYSTEM IS MOVING EAST-
SOUTHEASTWARD AT 10 KNOTS.
2. REMARKS: THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 12.1S 172.3W
IS NOW LOCATED NEAR 12.6S 171.4W, APPROXIMATELY 110 NM NORTH-NORTHWEST
OF PAGO PAGO. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS
IMPROVED CONSOLIDATION AND INCREASING CONVECTION. A 100103Z AMSU 89 GHZ
MICROWAVE IMAGE INDICATES IMPROVED ORGANIZATION WITH MULTIPLE
BANDS WRAPPING INTO A WELL DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). RECENT
SURFACE OBSERVATIONS FROM PAGO PAGO INDICATE A SEA LEVEL PRESSURE OF 1003.7
MB WITH A DECREASE OF 2 MB IN THE LAST 24 HOURS. UPPER LEVEL ANALYSIS
REVEALS THAT THE SYSTEM IS IN A REGION OF WEAK VERTICAL WIND SHEAR WITH
AN ANTICYCLONE OVER THE SYSTEM ENHANCING OUTFLOW. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE
IS ESTIMATED TO BE NEAR 1000 MB. DUE TO INCREASED CONSOLIDATION OF THE LLCC,
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN
THE NEXT 24 HOURS IS GOOD.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 110530Z.
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9810020900 116S1747W  15
9810020906 119S1741W  15
9810020912 120S1732W  15
9810020918 121S1723W  15
9810021000 126S1714W  15