WTPS21 PGTW 081430
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99P)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
080 NM EITHER SIDE OF A LINE FROM 18.5S 173.2E TO 20.1S 174.9E
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 AT 081200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 18.6S 173.3E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 03
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99P) PREVIOUSLY LOCATED 
NEAR 18.4S 173.0E IS NOW LOCATED NEAR 18.6S 173.3E, APPROXIMATELY 
278 NM WEST-SOUTHWEST OF NADI, FIJI. ANIMATED MULTISPECTRAL 
SATELLITE IMAGERY (MSI) AND A 080716Z AMSR2 91GHZ MICROWAVE IMAGE 
SHOW CONCENTRATED CONVECTION DISPLACED TO THE NORTHWEST OF A WELL-
DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) WITH WEAK CONVECTIVE 
BANDS ORIENTED IN A NORTH-SOUTH ARC ON THE EASTERN PERIPHERY. A 
08948Z ASCAT BULLSEYE FURTHER REVEALS A LARGE SWATH OF 30-35 KNOT 
WINDS MIRRORING THE CONVECTIVE BANDS ON THE EASTERN EDGE OF THE LLCC 
WITH 20 KTS WRAPPING INTO THE LLCC IN THE REMAINING QUADRANTS. 
ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR TROPICAL 
CYCLONE DEVELOPMENT WITH MODERATE RADIAL OUTFLOW ALOFT, MODERATE (15-
20KTS) VERTICAL WIND SHEAR (VWS), AND WARM (29C) SEA SURFACE 
TEMPERATURES (SST). GLOBAL MODELS AGREE THAT 99P WILL CONTINUE TO 
STRENGTHEN AS IT TRACKS GENERALLY SOUTH-SOUTHEAST. MAXIMUM SUSTAINED 
SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL 
PRESSURE IS ESTIMATED TO BE NEAR 1000 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 
091430Z.
//
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