TC 11S(FREDDY): peaked at CAT 5 US now CAT 4 //TC 13S(DINGANI): final warning//Invest 99W//Invest 91P//16/15utc

JTWC IS ISSUING 12HOURLY WARNINGS ON TC 11S(FREDDY). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON 11S, 13S AND INVEST 91P.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE (TC) 11S HAS WEAKENED OVER THE PAST 12 HOURS WITH WARMING CLOUD TOP TEMPERATURES AND A COOLING EYE TEMPERATURE EVIDENT IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY. ADDITIONALLY, EIR IMAGERY DEPICTS A MORE OBLONG STRUCTURE TO BOTH THE EYE AND SYSTEM WITH A BREAK IN THE EYEWALL OVER THE EASTERN QUADRANT. A 161056Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS A SYMMETRIC CORE WITH A SMALL 15NM DIAMETER MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. ANIMATED WATER VAPOR IMAGERY CONTINUES TO SHOW RADIAL OUTFLOW THUS ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE. BASED ON THE STEADY WEAKENING TREND SINCE ABOUT 160000Z, DVORAK DATA-T ESTIMATES HAVE DECREASED TO THE T5.5-T6.0 (102-115 KNOTS) RANGE, HOWEVER, THE INITIAL INTENSITY IS HELD CLOSER TO THE PGTW, DEMS, FMEE CURRENT INTENSITY ESTIMATES OF 6.5 (127 KNOTS). IN GENERAL, OBJECTIVE ESTIMATES RANGE FROM 110-120 KNOTS TO INCLUDE SATCON, ADT, AIDT, OPEN-AIIR AND DMN.

A 161056Z SSMIS 91GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS A SYMMETRIC CORE WITH A SMALL 15NM DIAMETER MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC 11S WILL TRACK WESTWARD THROUGH TAU 48 ALONG THE NORTHERN PERIPHERY OF THE STR. AFTER TAU 48, THE SYSTEM WILL TURN WEST-SOUTHWESTWARD AS THE STR REORIENTS IN RESPONSE TO AN APPROACHING MAJOR SHORTWAVE TROUGH. TC 11S SHOULD WEAKEN STEADILY DUE TO DRY AIR ENTRAINMENT AND POSSIBLY COOL UPWELLING WATER THROUGH THE FORECAST PERIOD WITH A GRADUAL DECREASE TO 100 KNOTS BY TAU 120 AS THE SYSTEM APPROACHES THE EAST COAST OF MADAGASCAR.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH A 120NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72. AFTER TAU 72, THE CROSS-TRACK SPREAD WILL INCREASE TO 250NM BY TAU 120 WITH INCREASING UNCERTAINTY IN THE EXACT FORECAST TRACK. BOTH THE ECMWF (EPS) AND GFS (GEFS) ENSEMBLES INDICATE A HIGH PROBABILITY OF LANDFALL OCCURRING OVER CENTRAL MADAGASCAR. THE 160000Z COAMPS-TC ENSEMBLE INDICATES RAPID INTENSIFICATION IS UNLIKELY, HOWEVER, IT DOES SHOW A 40 PERCENT PROBABILITY OF MODERATE INTENSIFICATION IN THE TAU 36 TO TAU 60 TIME PERIOD. RELIABLE INTENSITY GUIDANCE SUPPORTS A STEADY WEAKENING TREND THROUGH THE FORECAST PERIOD, HOWEVER, DECAY-SHIP (GFS VERSION) DOES INDICATE A MODEST 10-KNOT INCREASE FROM 115 TO 125 KNOTS IN THAT SAME TIME RANGE.

REMARKS: 160900Z POSITION NEAR 31.5S 67.7E. 16FEB23. TROPICAL CYCLONE (TC) 13S (DINGANI), LOCATED APPROXIMATELY 851 NM SOUTHEAST OF PORT LOUIS, MAURITIUS, HAS TRACKED SOUTHWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A SHALLOW, WELL-DEFINED LOW-LEVEL CIRCULATION WITH NO DEEP CONVECTION. THE SYSTEM IS LOCATED UNDER AN UPPER-LEVEL SUBTROPICAL TROUGH, POLEWARD OF THE SUBTROPICAL JET WITH HIGH VERTICAL WIND SHEAR AND A DRY ATMOSPHERE. THE SYSTEM HAS STEADILY WEAKENED WITHIN AN UNFAVORABLE ENVIRONMENT WITH COOL SST (22-23C) AND PERSISTENT HIGH VWS, AND IS EXPECTED TO DISSIPATE BY TAU 12. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 160600Z IS 17 FEET.

THE AREA OF CONVECTION (INVEST 99W) PREVIOUSLY LOCATED NEAR 6.0N 134.4E IS NOW LOCATED NEAR 5.7N 135.3E, APPROXIMATELY 106 NM SOUTH-SOUTHEAST OF PALAU. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A BROAD LOW-LEVEL CIRCULATION WITH DEEP CONVECTION OFFSET IN THE WESTERN SEMICIRCLE. RECENT SURFACE OBSERVATIONS AT PALAU REVEAL WINDS UP TO 10 KNOTS JUST TO THE NORTH OF THE SYSTEM. INVEST 99W IS CURRENTLY POSITIONED ALONG THE SOUTHEASTERN EDGE OF AN EXTENSIVE NORTHEAST SURGE FLOW (25-30 KNOTS). ENVIRONMENTAL ANALYSIS INDICATES UNFAVORABLE CONDITIONS WITH HIGH (40-50KT) EASTERLY VWS AND MINIMAL OUTFLOW ALOFT. SST REMAINS CONDUCIVE AT A WARM 28-29C. GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT 99W WILL HAVE LITTLE DEVELOPMENT AS IT TRACKS NORTHWESTWARD OVER THE NEXT 24-48 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.

GLOBAL MODELS ARE IN GENERAL AGREEMENT THAT 99W WILL HAVE LITTLE DEVELOPMENT AS IT TRACKS NORTHWESTWARD OVER THE NEXT 24-48 HOURS.

THE AREA OF CONVECTION (INVEST 91P) PREVIOUSLY LOCATED NEAR 14.9S 139.5E IS NOW LOCATED NEAR 15.0S 139.1E, APPROXIMATELY 102 NM NORTH OF MORNINGTON ISLAND, AUSTRALIA. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND ANIMATED RADAR IMAGERY DEPICT A DISORGANIZED LOW-LEVEL CIRCULATION (LLC). A 160032Z METOP-C IMAGE SHOWS A BROAD AND ELONGATED CIRCULATION. ENVIRONMENTAL ANALYSIS REVEALS THAT INVEST 91P IS IN A MARGINAL ENVIRONMENT FOR INTENSIFICATION DUE TO MODERATE TO HIGH (20-25) VWS, MODERATE POLEWARD OUTFLOW ALOFT, AND VERY WARM (29-30C) SST. GLOBAL MODELS ARE IN AGREEMENT THAT INVEST 91P WILL TRACK SOUTHEASTWARD BEFORE RECURVING SOUTHWEST, MAKING LANDFALL OVER NORTHERN AUSTRALIA WITHIN THE NEXT 24 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 25 TO 30 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 998 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS LOW.