WTPN21 PGTW 280600
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
160 NM EITHER SIDE OF A LINE FROM 10.3N 146.0E TO 12.7N 139.6E 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 20 TO 25 KNOTS. METSAT IMAGERY AT 280530Z INDICATES 
THAT A CIRCULATION CENTER IS LOCATED NEAR 10.6N 145.5E. THE SYSTEM IS 
MOVING WEST-NORTHWESTWARD AT 14 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 93W) PREVIOUSLY LOCATED 
NEAR 9.9N 146.7E IS NOW LOCATED NEAR 10.6N 145.5E, APPROXIMATELY 173 
NM SOUTH-SOUTHEAST OF GUAM. ANIMATED MULTISPECTRAL SATELLITE IMAGERY 
DEPICTS A SLOWLY-DEVELOPING LOW-LEVEL CIRCULATION (LLC) WITH LOW-LEVEL 
CLOUD LINES WRAPPING INTO A WEAKLY-DEFINED CENTER, AND DEEP CONVECTION 
FLARING OVER THE LLC. A 280336Z AMSR2 89GHZ COLOR COMPOSITE MICROWAVE 
IMAGE SHOWS INCIPIENT LOW-LEVEL BANDING OVER THE SOUTHERN SEMICIRCLE 
WITH EXTENSIVE FRAGMENTED BANDING OVER THE NORTHERN SEMICIRCLE 
ASSOCIATED WITH CONVERGENT LOW-LEVEL EASTERLIES. SURFACE OBSERVATIONS 
FROM GUAM INDICATE VIGOROUS NORTHEASTERLY WINDS AT 15-20 KNOTS GUSTING 
TO 25-30 KNOTS. ENVIRONMENTAL ANALYSIS INDICATES GENERALLY FAVORABLE 
CONDITIONS WITH LOW TO MODERATE (10-15KTS) VWS, WARM (29-30C) SEA 
SURFACE TEMPERATURES AND GOOD POLEWARD OUTFLOW. OVER THE NEXT ONE TO 
TWO DAYS, GLOBAL MODELS INDICATE GRADUAL DEVELOPMENT AND CONSOLIDATION 
INTO A DISCRETE LLC WITH A GENERALLY WEST-NORTHWESTWARD TO 
NORTHWESTWARD TRACK SOUTH AND SOUTHWEST OF GUAM. HOWEVER, VIGOROUS 
NORTHEASTERLY WINDS WILL MAINTAIN OVER GUAM DURING THIS PERIOD. 
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 
290600Z.//
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