WTPN21 PGTW 251500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 95W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 140 NM 
EITHER SIDE OF A LINE FROM 15.8N 148.8E TO 18.5N 145.4E 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 20 TO 25 KNOTS. METSAT IMAGERY AT 251430Z INDICATES THAT A 
CIRCULATION CENTER IS LOCATED NEAR 16.1N 148.3E. THE SYSTEM IS MOVING 
NORTHWESTWARD AT 11 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 95W) PREVIOUSLY LOCATED NEAR 
15.5N 149.3E IS NOW LOCATED NEAR 16.1N 148.3E, APPROXIMATELY 157 NM 
EAST-NORTHEAST OF SAIPAN. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY 
DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER, WITH FLARING 
DEEP CONVECTION ALONG THE EASTERN AND SOUTHERN PERIPHERIES. A 251044Z 
MHS 89GHZ MICROWAVE IMAGE SHOWS BROAD CONVECTIVE BANDING, WITH WEAK LOW-
LEVEL STRUCTURE. RECENT SCATTEROMETRY DATA INDICATES A SWATH OF 20 TO 25 
KNOT CONVERGENT WINDS OVER THE EASTERN AND SOUTHERN SEMICIRCLES, WHICH 
IS FUELING THE AFOREMENTIONED EXTENSIVE DEEP CONVECTIVE BURSTS.       
ENVIRONMENTAL ANALYSIS INDICATES MARGINALLY FAVORABLE CONDITIONS, WITH 
WARM SEA SURFACE TEMPERATURES (29-30 C) AND GOOD EQUATORWARD OUTFLOW 
ALOFT, OFFSET BY MODERATE TO HIGH (20 TO 25 KNOTS) VERTICAL WIND SHEAR. 
GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE SYSTEM WILL CONTINUE TO 
TRACK NORTHWESTWARD WITH GRADUAL INTENSIFICATION OVER THE NEXT 12-36 
HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 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 
261500Z.//
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