BOB: TC 01B: a rare March Cyclone//14S and 18P: subtropical// Invest 96P// Invest 97S: slow development expected, 05/03utc, 06utc UPDATE

JTWC IS ISSUING 6HOURLY WARNINGS ON TC 01B. 3HOURLY SATELLITE BULLETINS ARE ISSUED ON 01B, 14S,18P AND INVEST 96P.

05/07UTC.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 01B IS CURRENTLY TRACKING NORTHEAST UNDER THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR), UNLIKE PREVIOUSLY FORECAST THE SYSTEM HAS NOT YET TURNED TOWARD THE MAINLAND OF SOUTHEASTERN INDIA. HOWEVER, BY 12H, AS THE STR CONTINUES TO BUILD IN FROM THE NORTHEAST, THE SYSTEM WILL BE FORCED TO TRACK WEST- SOUTHWESTWARD. TC 01B IS FORECAST TO REACH A PEAK INTENSITY OF 40 KNOTS WHILE STILL IN A MARGINAL ENVIRONMENT CHARACTERIZED BY WARM (27-28 C) SEA SURFACE TEMPERATURES (SST), LOW (5-10 KTS) VERTICAL WINDS SHEAR (VWS) AND GOOD POLEWARD AND WESTWARD OUTFLOW, OFF SET BY WEAK DRY AIR ENTRAINMENT. BETWEEN 12H AND 36H, SIGNIFICANT DRY AIR ENTRAINMENT, INCREASING VWS AND LAND INTERACTION WILL STEADILY WEAKEN TC 01B. BY 48H, THE INTENSITY IS FORECAST TO FALL BELOW 25 KNOTS AS ITS MID AND UPPER LEVELS BECOME FULLY ENTRAINED BY DRY AIR AFTER WHICH FULL DISSIPATION IS EXPECTED.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A STEADY AREA OF CONVECTION OVER AN ASSESSED LOW LEVEL CIRCULATION CENTER (LLCC). A 042254Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS LOW LEVEL BANDING WITH AREAS OF CONVECTION ON THE WESTERN AND EASTERN PERIPHERIES OF THE LLCC. OTHER SCATTEROMETRY DATA REVEALS A RELATIVELY SYMMETRICAL CIRCULATION WITH 30-35KT WINDS IN THE NORTHWEST QUADRANT. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON PGTW FIX, EIR AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON AFOREMENTIONED SCATTEROMETRY DATA, PGTW AND AUTOMATED DVORAKS.

MODEL DISCUSSION: AS THE STR BUILDS TO THE NORTHEAST NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT ABOUT THE FORECAST TRACK WITH A 75KM SPREAD IN SOLUTIONS AT 48H. THE JTWC FORECAST TRACK IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE MODERATE MODEL SPREAD AND THE UNCERTAINTY OF THE TIMING OF WHEN THE RIDGE TO THE EAST- NORTHEAST WILL BUILD. RELIABLE MODEL INTENSITY GUIDANCE IS IN UNANIMOUS AGREEMENT WITH A PEAK IN INTENSITY AT 12H FOLLOWED BY A STEADY WEAKENING TREND THROUGH THE FORECAST PERIOD.

THE AREA OF CONVECTION (REMNANTS OF 14S) PREVIOUSLY LOCATED NEAR 29.5S 79.5E IS NOW LOCATED NEAR 30.5S 79.8E, APPROXIMATELY 2020 KM SOUTHEAST OF PORT MATHURIN. THE SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL STORM, GENERALLY CHARACTERIZED AS HAVING BOTH TROPICAL AND MID-LATITUDE CYCLONE FEATURES. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 050049Z SSMIS 91GHZ MICROWAVE IMAGE DEPICT AN ELONGATED AND PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLC) WITH A PROMINENT DEFORMATION ZONE ON THE POLEWARD EDGE. ENVIRONMENTAL ANALYSIS INDICATES THE CONDITIONS FOR TROPICAL CYCLONE DEVELOPMENT ARE UNFAVORABLE WITH COOL SEA SURFACE TEMPERATURES (23-24 C), DRY AIR DOMINATING THE LOWER LEVELS AND HIGH (20-30 KTS) VERTICAL WIND SHEAR AS 14S IS FULLY EMBEDDED IN THE MID- LATITUDE WESTERLIES. GLOBAL MODELS INDICATE THAT 14S WILL REMAIN EMBEDDED IN THE MID-LATITUDE JET AND TRACK EAST-SOUTHEAST. FOR HAZARDS AND WARNINGS, REFERENCE THE FLEET WEATHER CENTER SAN DIEGO HIGH WINDS AND SEAS PRODUCT OR REFER TO LOCAL WMO DESIGNATED FORECAST AUTHORITY. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 40 TO 45 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 991 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

THE AREA OF CONVECTION (INVEST 97S) PREVIOUSLY LOCATED NEAR 15.6S 55.9E IS NOW LOCATED NEAR 15.7S 55.7E, APPROXIMATELY 560 KM EAST OF MADAGASCAR. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 041515Z SSMIS 91GHZ MICROWAVE IMAGE DEPICT A CONSOLIDATING LOW LEVEL CIRCULATION (LLC) OBSCURED BY FLARING CONVECTION WITH FRAGMENTED BANDING BEGINNING TO WRAP INTO THE DISTURBANCE. UPPER LEVEL ANALYSIS INDICATES FAVORABLE CONDITIONS FOR DEVELOPMENT TO INCLUDE GOOD OUTFLOW ALOFT, LOW TO MODERATE VERTICAL WIND SHEAR (10-20KTS), AND WARM SEA SURFACE TEMPRETURES (28-29C). GLOBAL MODELS ARE IN GOOD AGREEMENT THAT 97S WILL REMAIN GENERALLY QUASI-STATIONARY AS IT STEADILY INTENSIFIES EAST OF MADAGASCAR. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.