Tropical Cyclone Formation Alert issued for Invest 91P, 17/12utc

JTWC IS ISSUING 3HOURLY SATELLITE BULLETINS ON INVEST 91P.

FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN 220 KM EITHER SIDE OF A LINE FROM 13.7S 171.8E TO 15.4S 170.0E 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 25 TO 30 KNOTS. METSAT IMAGERY AT 170600Z INDICATES THAT A CIRCULATION CENTER IS LOCATED NEAR 13.8S 171.9E. THE SYSTEM IS MOVING SOUTHEASTWARD AT 07 KM/H. 2. REMARKS: THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 13.7S 171.E IS NOW LOCATED NEAR 13.8S 171.9E, APPROXIMATELY 313 NM NORTHEAST OF PORT VILA, VANUATU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH FORMATIVE BANDING FEEDING IN FROM THE NORTHEAST. A 170703Z SSMIS MICROWAVE IMAGE SHOWS DEEP CONVECTION OVER THE LOW LEVEL CIRCULATION (LLC) AND CURVED, CONVECTIVE BANDING TO THE SOUTHEAST WRAPPING INTO THE EASTERN QUADRANT OF THE LLC. A 170714Z ASCAT (METOP-C) IMAGERY REVEALS 20-24 KNOT WINDS TO THE SOUTH-SOUTHEAST OF THE LLC. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH LIGHT TO MODERATE (10-15 KNOTS) VERTICAL WIND SHEAR AND ROBUST RADIAL OUTFLOW. DYNAMIC MODELS INDICATE GRADUAL INTENSIFICATION OVER THE NEXT 24-36HRS AS THE SYSTEM TRACKS TO THE SOUTHWEST. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB WITH WARM (29-30 C) SEA SURFACE TEMPERATURES. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

DYNAMIC MODELS INDICATE GRADUAL INTENSIFICATION OVER THE NEXT 24-36HRS AS THE SYSTEM TRACKS TO THE SOUTHWEST.