WTPN21 PGTW 040900 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 22.5N 139.9E TO 24.6N 137.9E 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 040600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 22.8N 139.8E. THE SYSTEM IS MOVING NORTHWARD AT 07 KNOTS. 2. REMARKS: THE AREA OF CONVECTION (INVEST 90W) PREVIOUSLY LOCATED NEAR 21.8N 139.3E IS NOW LOCATED NEAR 22.3N 139.1E, APPROXIMATELY 201 NM SOUTHEAST OF IWO TO. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS BUILDING, DEEP CONVECTION THAT HAS CONTINUED TO CONSOLIDATE AND WRAP INTO AN OBSCURED LOW LEVEL CIRCULATION CENTER. DESPITE THE CONSOLIDATING CONVECTION, THE LOW LEVELS REMAIN DISORGANIZED AS EVIDENT IN RECENT MICROWAVE IMAGERY FROM 040404Z AMSR2 36GHZ AND 040646Z SSMIS 37GHZ RETRIEVALS. FURTHERMORE, DATA FROM A 032352Z ASCAT-A PASS REVEALS THAT THE LOW LEVEL CIRCULATION REMAINS BROAD AND ELONGATED ALONG A NORTHEAST TO SOUTHWEST AXIS. THE SCATTEROMETRY DATA FURTHER DEPICTS 10-15 KT WINDS ALONG THE PERIPHERY OF THE LOW LEVEL CIRCULATION AND STRONGER, 20-30 KTS WINDS DISPLACED > 100 NM TO THE SOUTHEAST. INVEST 90W IS TRACKING SLOWLY NORTHWESTWARD AND THROUGH AN ENVIRONMENT CONDUCIVE FOR FURTHER DEVELOPMENT WITH LOW (5-10 KT) VERTICAL WIND SHEAR, WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES AND ROBUST EQUATORWARD OUTFLOW ALOFT. NUMERICAL MODEL SOLUTIONS ARE IN DISAGREEMENT OVER THE OVERALL TRACK OF THE SYSTEM CENTER AND THERE IS A SIGNIFICANT DIVERGENCE IN MODEL TRACK GUIDANCE. NAVGEM AND GFS SOLUTIONS PREDICT A NORTH TO NORTHWESTWARD TRACK WHILE ECMWF AND UKMET CALCULATE WESTWARD SOLUTIONS. ENSEMBLE MEMBERS IN BOTH GFS AND ECMWF SOLUTIONS BIFURCATE, SUGGESTING BOTH MODELS CONSIDER THE DISPARATE DETERMINISTIC SOLUTIONS. DESPITE THIS DISAGREEMENT IN MODEL SOLUTIONS, THE SYSTEM IS EXPECTED TO TRACK GENERALLY NORTHWESTWARD OVER THE NEXT 24 HOURS AS IT CONTINUES TO CONSOLIDATE IN THE FAVORABLE ENVIRONMENT. 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 050900Z.// NNNN