WTPN21 PGTW 220300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 97W)// RMKS/ 1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 160 NM EITHER SIDE OF A LINE FROM 16.4N 133.4E TO 22.6N 128.4E 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 15 TO 20 KNOTS. METSAT IMAGERY AT 220300Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 16.8N 133.2E. THE SYSTEM IS MOVING NORTH-NORTHWESTWARD AT 08 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 97W) PREVIOUSLY LOCATED NEAR 14.6N 133.3E IS NOW LOCATED NEAR 16.8N 133.2E, APPROXIMATELY 650 NM SOUTH-SOUTHEAST OF KADENA AIR BASE, OKINAWA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A RAPIDLY CONSOLIDATING LOW-LEVEL CIRCULATION (LLC), WITH FORMATIVE BANDING AND LOW-LEVEL CLOUD LINES WRAPPING INTO THE CENTER. A 220113Z ASCAT-C BULLSEYE IMAGE REVEALS A BROAD CIRCULATION, WITH PATCHY 20-25 KNOT WINDS OVER THE EASTERN QUADRANT AND 5-10 KNOT WINDS OVER THE WESTERN SEMICIRCLE. A 220019Z MHS 89GHZ MICROWAVE IMAGE DEPICTS FRAGMENTED DEEP CONVECTIVE BANDING AROUND THE NORTHERN PERIPHERY, WITH IMPROVED SHALLOW BANDING WRAPPING INTO A BROAD CENTER. ENVIRONMENTAL ANALYSIS REVEALS A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (15-20 KNOTS) VERTICAL WIND SHEAR OFFSET BY DUAL CHANNEL OUTFLOW. SST VALUES ARE FAVORABLE AT 30-31C. INVEST 97W HAS FORMED ALONG THE EASTERN PERIPHERY OF AN AREA OF BROAD MONSOONAL FLOW AND IS EXPECTED TO TRACK POLEWARD ALONG THE EASTERN PERIPHERY OF THIS COMPLEX SYSTEM OVER THE NEXT 24 TO 36 HOURS. AFTER THIS PERIOD, THE SYSTEM MAY DISSIPATE AND MERGE WITH A DEVELOPING MONSOON DEPRESSION SOUTH OF OKINAWA. THIS MONSOON DEPRESSION IS FORECAST TO PRODUCE AN EXTENSIVE SWATH OF GALE-FORCE WINDS ALONG THE EASTERN AND NORTHERN PERIPHERIES. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 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 230300Z.// NNNN