WTPN21 PGTW 260600
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 91W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 9.2N 141.8E TO 12.7N 138.1E
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 260600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 9.3N 141.7E. THE SYSTEM IS MOVING NORTHWARD AT 03 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91W) PREVIOUSLY LOCATED NEAR 
8.7N 141.6E IS NOW LOCATED NEAR 9.3N 141.7E, APPROXIMATELY 211 NM EAST 
OF YAP. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS BROAD TURNING 
AND A WEAK LOW-LEVEL CIRCULATION (LLC) WITH IMPROVED CONVECTION AND 
FORMATIVE BANDING WRAPPING INTO THE LLC ALONG THE SOUTHERN PERIPHERY. 
THE FORMATIVE BANDING IS FURTHER EVIDENT IN A 252135Z SSMIS 91GHZ 
MICROWAVE IMAGE. LOCAL OBSERVATIONS FROM YAP REVEAL A DEEPENING PRESSURE 
CENTER WITH A 24 HOUR PRESSURE FALL OF 0.6 MB. INVEST 91W REMAINS IN A 
MARGINAL ENVIRONMENT FOR DEVELOPMENT DUE TO NORTHERLY OUTFLOW FROM TY 
05W PLACING THE SYSTEM UNDER MODERATE TO HIGH (20-25KT) VERTICAL WIND 
SHEAR. SEA SURFACE TEMPERATURES REMAIN CONDUCIVE AT A WARM 29-30C. 
GLOBAL MODELS ARE IN STRONG AGREEMENT THAT INVEST 91W WILL STEADILY 
CONSOLIDATE AS IT TRACKS NORTH-NORTHWESTWARD 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 HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 
270600Z.//
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