WTPN21 PGTW 271500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 93W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
130 NM EITHER SIDE OF A LINE FROM 18.6N 144.2E TO 20.9N 136.6E
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 271200Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 18.6N 143.9E. THE SYSTEM IS MOVING NORTHWARD AT 11 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED NEAR 
16.4N 143.5E IS NOW LOCATED NEAR 18.0N 143.9E, APPROXIMATELY 316 NM NORTH 
OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 270805Z SSMIS 
91 GHZ IMAGE DEPICT A BROAD AREA OF SHARP TROUGHING WITH PERSISTENT, DEEP 
CONVECTIVE BANDING HIDING THE PROSPECTIVE LOW LEVEL CIRCULATON CENTER 
(LLCC). A 271130Z ASCAT-C PARTIAL PASS SHOWS 15-20KT WINDS TO THE EAST OF 
THE ASSESSED CENTER. ENVIRONMENTAL ANALYSIS REVEALS FAVORABLE CONDITIONS 
FOR DEVELOPMENT WITH WARM (29-30 C) SST AND ROBUST POLEWARD OUTFLOW ALOFT 
OFFSET BY MODERATE (15-20KTS) VERTICAL WIND SHEAR. GLOBAL MODELS INDICATE 
93W WILL TRACK SLOWLY WESTWARD WITH STEADY DEVELOPMENT OVER THE NEXT 48 
HOURS. THE SYSTEM WILL LIKELY STALL NEAR THE WEST OF THE NORTHERN 
MARIANAS WITH STRONG MONSOONAL FLOW PERSISTING OVER THE REGION, AIDING IN 
ITS DEEPENING AND DEVELOPMENT. 
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 18 TO 23 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 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 
281500Z.
//
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