WTPN21 PGTW 121130
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
REF/A/JOINT TYPHOON WRNCEN PEARL HARBOR HI/121121Z APR 21//
AMPN/REF IS TROPICAL CYCLONE FORMATION ALERT (WTPN21 PGTW 121130)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 5.6N 141.5E TO 8.6N 140.8E
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 18 TO 23 KNOTS. METSAT
IMAGERY AT 120600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 5.9N 141.5E. THE SYSTEM IS MOVING NORTHWESTWARD AT 07 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 94W) PREVIOUSLY LOCATED 
NEAR 5.6N 143.1E IS NOW LOCATED NEAR 5.9N 141.5E, APPROXIMATELY 488 
NM SOUTH-SOUTHWEST OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY AND A 120858Z SSMIS 91GHZ MICROWAVE IMAGE REVEAL FLARING, 
DEEP CONVECTION IN THE NORTHEASTERN PERIPHERY OF THE ASSESSED LOW 
LEVEL CIRCULATION CENTER (LLCC). A 121030Z ASCAT-A SCATTEROMETRY 
PASS INDICATES A DISORGANIZED LLCC ON THE SOUTHWESTERN EDGE OF 
FLARING DEEP CONVECTION, WITH WINDS OF 20-25 KTS IN THE NORTHEASTERN 
QUADRANT OF THE CIRCULATION AND 15-20 KTS ELSEWHERE. INVEST 94W IS 
IN A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT WITH ROBUST 
WESTWARD AND EQUATORWARD OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND 
SHEAR, AND WARM (29-30C) SEA SURFACE TEMPERATURES. GLOBAL MODELS ARE 
IN GOOD AGREEMENT THAT INVEST 94W WILL STEADILY INTENSIFY AS IT 
TRACKS TO THE NORTHWEST OVER THE NEXT 24 HOURS. 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. THIS SUPERSEDES REF A.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
131130Z.
//
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