WTXS21 PGTW 082130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 99S)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
070 NM EITHER SIDE OF A LINE FROM 17.7S 120.6E TO 19.6S 121.8E
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 081800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 17.9S 120.8E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 08
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 99S), PREVIOUSLY LOCATED 
NEAR 15.8S 118.9E IS NOW LOCATED NEAR 17.9S 120.8E, APPROXIMATELY 81 
NM WEST OF BROOME, AUSTRALIA. ANIMATED ENHANCED INFRARED IMAGERY 
(EIR) DEPICTS PERSISTENT CONVECTION OBSCURING A LOW LEVEL 
CIRCULATION CENTER (LLCC). A 081707Z AMSR2 89GHZ MICROWAVE IMAGE 
REVEALS FORMATIVE BANDING WRAPPING INTO A LLCC. INVEST 99S IS IN A 
MODERATELY FAVORABLE ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW AND 
WARM (30-31C) SEA SURFACE TEMPERATURES (SST) OFFSET BY MODERATE (10-
20 KT) VERTICAL WIND SHEAR (VWS). GLOBAL MODELS GENERALLY AGREE THAT 
99S WILL BRIEFLY INTENSIFY BEFORE MAKING LANDFALL OVER AUSTRALIA 
AROUND TAU 12. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 28 
TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 
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 
092130Z.//
NNNN