WTPN21 PHNC 180730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 98E)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 12.3N 116.9W TO 11.3N 122.1W
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 180600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 12.2N 117.3W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 14
KNOTS.
2. REMARKS:
AN AREA OF CONVECTION (INVEST 98E) IS LOCATED NEAR 12.2N
117.3W, APPROXIMATELY 420NM SOUTHWEST OF CLARION ISLAND. ANIMATED 
ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WELL-DEFINED LOW-
LEVEL CIRCULATION CENTER (LLCC) EMBEDDED WITHIN THE NEAR-EQUATORIAL 
TROUGH (NET). THIS IS FURTHER DEPICTED BY A 180415Z METOP-B ASCAT PASS 
REVEALING THE WELL-DEFINED CIRCULATION WITH SLIGHTLY ELEVATED WINDS 
ALONG THE SOUTHERN PERIPHERY. ENVIRONMENTAL ANALYSIS INDICATES A 
MARGINALLY FAVORABLE AREA FOR DEVELOPMENT WITH WARM (28-29 C) SEA 
SURFACE TEMPERATURES, ROBUST AMOUNTS OF MOISTURE SURROUNDING 98E, 
MODERATE EQUATORWARD OUTFLOW ALOFT, OFFSET BY MODERATE TO HIGH (20-25 
KTS) VERTICAL WIND SHEAR (VWS). MODEL GUIDANCE IS IN AGREEMENT WITH 
GRADUAL DEVELOPMENT OF 98E WITH THE EXCEPTION OF GFS AND THE 
CORRESPONDING ENSEMBLE GUIDANCE, WHICH IS MORE CONSERVATIVE AS THE 
SYSTEM TRANSITS GENERALLY WESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE 
ESTIMATED AT 18 TO 23 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO 
BE NEAR 1005 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 
190730Z.//
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