WTPN21 PGTW 262200
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
120 NM EITHER SIDE OF A LINE FROM 16.0N 142.7E TO 22.0N 139.2E
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 261800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 16.1N 142.6E. THE SYSTEM IS MOVING NORTHWESTWARD AT 04
KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED NEAR 
15.2N 145.4E IS NOW LOCATED NEAR 16.1N 142.6E, APPROXIMATELY 206 NM 
NORTHWEST OF GUAM. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A 
DEEPENING AND EXPANDING SYSTEM WITH SIGNS OF FORMATIVE BANDING IN THE 
NORTHWEST QUADRANT FEEDING INTO AN ASSESSED LOW LEVEL CIRCULATION (LLC). 
A 261214Z ASCAT-C PASS SHOWS A SHARP TROUGH AT THE SURFACE WITH 20 KNOT 
WINDS IN THE SOUTHEAST QUADRANT ALONG WITH A SMALL PATCH OF 25 KNOT WINDS 
LIKELY ASSOCIATED WITH THUNDERSTORM ACTIVITY. ANALYSIS INDICATES AN 
OVERALL FAVORABLE ENVIRONMENT WITH A WESTWARD TRANSITING TROPICAL UPPER 
TROPOSPHERIC TROUGH (TUTT) CELL. THE SAME TUTT CELL IS ENHANCING POLEWARD 
OUTFLOW THAT IS OFFSETTING THE SUBSIDENCE. ADDITIONALLY, VERTICAL WIND 
SHEAR IS LOW (10-15KTS) TOWARDS THE CENTER OF THE LLC, AND VERY WARM (29-
30C) SEA SURFACE TEMPERATURES. NUMERICAL MODELS ARE IN GENERAL AGREEMENT 
THAT THE SYSTEM WILL TRACK NORTHWESTWARD AND DEEPEN OVER THE NEXT 24-48 
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 UPGRADED TO HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
272200Z.
//
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