WTPN21 PHNC 221930
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91C)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 10.7N 142.1W TO 12.0N 147.2W
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 23 TO 28 KNOTS. METSAT
IMAGERY AT 221800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 10.7N 142.3W. THE SYSTEM IS MOVING WESTWARD AT 06 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 91C) IS LOCATED NEAR 10.7N 
142.3W, APPROXIMATELY 914 NM SOUTHEAST OF HILO, HAWAII. ANIMATED 
MUTISPECTRAL SATELLITE IMAGERY DEPICTS INVEST 91C WITH A PARTIALLY 
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH FLARING CONVECTION 
ALONG THE NORTHERN AND SOUTHWESTERN PERIPHERIES. FORMATIVE BANDING CAN 
ALSO BE SEEN WRAPPING INTO THE SYSTEM ALONG THE SOUTHERN SEMICIRCLE. 
ENVIRONMENTAL ANALYSIS INDICATES THAT 91C IS IN A FAVORABLE 
ENVIRONMENT FOR DEVELOPMENT CHARACTERIZED BY GOOD POLEWARD AND 
EQUATORWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR, AND 
WARM (28-29C) SEA SURFACE TEMPERATURES. GLOBAL MODELS AGREE THAT 91C 
WILL STEADILY CONSOLIDATE OVER THE NEXT 24 HOURS AS IT CONTINUES TO 
TRACK GENERALLY WESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE 
ESTIMATED AT 23 TO 28 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED 
TO BE NEAR 1008 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 
231930Z.//
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