North Indian: after TC 03A, Invest 99B is another very rare August system//Invest 93W and Invest 96W, 18/03utc

JTWC IS ISSUING 3HOURLY SATELLITE BULLETINS ON INVEST 99B.

THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 18.4N 94.3E IS NOW LOCATED NEAR 18.9N 93.4E, APPROXIMATELY 362 NM SOUTHEAST OF KOLKATA, INDIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN AREA OF FLARING CONVECTION TO THE WEST AND SOUTH A LOW LEVEL CIRCULATION (LLC). ENVIRONMENTAL ANALYSIS INDICATES INVEST 99B IS IN AN AREA OF FAVORABLE CONDITIONS FOR TROPICAL DEVELOPMENT CHARACTERIZED BY ROBUST WESTWARD UPPER LEVEL OUTFLOW, A SMALL POCKET OF LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), A STRONG 850 MB VORTICITY SIGNATURE, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. MULTIPLE DETERMINISTIC MODELS INDICATE INVEST 99B WILL TRACK TO THE WEST-NORTHWEST AS A CIRCULATION, WITH GFS BEING THE MOST AGGRESSIVE FOR CONSOLIDATION AND INTENSITY. BOTH GEFS AND ECMWF ENSEMBLES HAVE MEMBERS THAT SHOW POTENTIAL TC DEVELOPMENT WHILE INVEST 99B TRANSITS THE NORTHERN BAY OF BENGAL. HIGH LEVELS OF VWS FROM THE TEJ AREA EXPECTED TO WEAKEN OVER THE NEXT 24-36 HOURS, INCREASING THE POSSIBILITY OF A RAPIDLY CONSOLIDATING SYSTEM. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 29 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 994 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

MULTIPLE DETERMINISTIC MODELS INDICATE INVEST 99B WILL TRACK TO THE WEST-NORTHWEST AS A CIRCULATION, WITH GFS BEING THE MOST AGGRESSIVE FOR CONSOLIDATION AND INTENSITY. BOTH GEFS AND ECMWF ENSEMBLES HAVE MEMBERS THAT SHOW POTENTIAL TC DEVELOPMENT WHILE INVEST 99B TRANSITS THE NORTHERN BAY OF BENGAL.