WTPN21 PGTW 290730
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 90W)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 6.0N 148.7E TO 10.5N 143.8E
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 290600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 6.2N 148.4E. THE SYSTEM IS MOVING NORTHWESTWARD AT 04 KNOTS.
2. REMARKS: AN AREA OF CONVECTION (INVEST 90W) HAS PERSISTED NEAR 
6.2N 148.4E, APPROXIMATELY 478 NM SOUTH-SOUTHEAST OF GUAM. ANIMATED 
MULTISPECTRAL SATELLITE IMAGERY, SUPPORTED BY A 290637Z SSMIS F-16 
91GHZ MICROWAVE IMAGE, DEPICTS DEEP CONVECTION CONSOLIDATING OVER A 
RAPIDLY TIGHTENING LOW LEVEL CIRCULATION CENTER (LLCC) WITH 
FORMATIVE DEEP CONVECTIVE BANDING WRAPPING IN FROM THE EAST AND 
SOUTH. A 290006Z METOP-C ASCAT PASS REVEALS TIGHT TROUGHING WITH AN 
EXTENSIVE SWATH OF HIGHER (20 TO 30 KNOTS) WINDS TO THE SOUTH BUT 
WITH WINDS OF ONLY 5-10 KNOTS ON NORTHERN SIDE OF THE BROAD 
CIRCULATION. 90W IS CURRENTLY IN A FAVORABLE ENVIRONMENT WITH 
EXCELLENT EQUATORWARD OUTFLOW AND VERY WARM (30 TO 31 CELSIUS) SEA 
SURFACE TEMPERATURES BEING SLIGHTLY OFFSET BY MODERATE (15 TO 25 
KNOT) VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 
90W WILL TRACK GENERALLY NORTH-NORTHWESTWARD, QUICKLY INTENSIFYING 
TO WARNING THRESHOLD OVER THE NEXT 48 HOURS OR LESS. 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 
300730Z.//
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